BEIRUT, July 13 -- Israel stepped up its campaign to force the release of two abducted soldiers Thursday, bombarding Beirut's airport, two Lebanese military air bases, a Hezbollah television station and other targets while imposing a blockade on Lebanon's ports and airspace. Hezbollah, the Lebanese militant group that captured the soldiers Wednesday in a cross-border raid, rained more than 80 rockets onto Israeli territory.

In a second attack on Beirut's international airport, Israeli helicopter gunships fired missiles at fuel tanks, setting at least one tank ablaze. Thick black smoke and orange flames shot up from the burning fuel, illuminating the night sky. Earlier in the day, Israeli warplanes had bombed the airport's runways, forcing it to close.

The Mediterranean port of Haifa, Israel's third-largest city, was hit by two rockets in Hezbollah's deepest strike into Israeli territory, authorities said. But Hezbollah, a Shiite Muslim organization supported by Syria and Iran, denied firing rockets at Haifa, which is located about 30 miles south of the Israeli-Lebanese border and has about 270,000 residents.

Although no casualties were reported in the attack on Haifa, Israel's ambassador to the United States, Daniel Ayalon, said the southernmost strike to date represented a "major escalation" of the fighting.

Secretary of State Condoleezza Rice, traveling with President Bush in Germany, urged Israel late Thursday to "exercise restraint" and called on Syria to exert pressure on Hezbollah to halt its attacks on Israel, Reuters news agency reported.

"It is extremely important that Israel exercise restraint in its acts of self defense," she told reporters in late-night comments aimed at tamping down Middle East tensions.

At the United Nations, the United States Thursday vetoed a Security Council resolution backed by Arab states that would have condemned Israel's two-week-old military offensive in the Gaza Strip and demanded the withdrawal of Israeli forces. The draft resolution, put forward by Qatar, accused Israel of using "disproportionate" force in Gaza in response to the capture of an Israeli soldier just outside the strip last month. The vote for the resolution was 10-1, with the United States casting its veto and four other countries -- Britain, Denmark, Peru and Slovakia -- abstaining.

As the death toll mounted, Israeli aircraft bombed two Lebanese air bases -- Rayak in the eastern Bekaa Valley and Kleiat in the north -- in the first strikes on Lebanon's military in the current conflict, authorities said. The bases, both located near the border with Syria, are used by the Lebanese army's fleet of about 30 old U.S.-made helicopters. The Lebanese military currently has no operational fixed-wing aircraft.

There was no immediate word on casualties in the raids, but Lebanese authorities reported that other strikes have killed at least 53 people and wounded more than 100. The Israeli bombardment was the heaviest against Lebanon since Israeli forces invaded the country in 1982 to force the withdrawal of Palestinian guerrillas.

In Israel, two women were killed and more than 40 other people were wounded when Hezbollah fighters fired more than 80 rockets into the northern part of the country, hitting nearly 20 towns and villages in the fiercest barrages in a decade. At least eight Israeli soldiers also have been reported killed since the violence erupted Wednesday.

The Israeli military said it struck the Beirut airport because it serves as "a central hub for the transfer of weapons and supplies" to Hezbollah. It said the attacks on the runways and fuel tanks were "aimed to prevent the transport of weapons and the hostages from the area."

The two sides also escalated their war of words Thursday, with Israeli officials saying they would strike anywhere in Lebanon -- including Beirut -- in order to eradicate Hezbollah's presence along Israel's northern border. A spokesman for the Shiite Muslim militant group said Hezbollah would respond to such an offensive by launching rockets at Haifa.

Among the Lebanese casualties from the Israeli barrages of bombs and artillery shells were at least two large families, television stations reported. News cameras filmed the charred, dismembered remains of one of the youngest victims, identified by a morgue official as a nine-month-old baby from the village of Dweir.

In Israel, a barrage of rockets fired from Lebanon landed in the resort town of Nahariya shortly after 7 a.m. A 40-year-old woman died there when she was blown off her fifth-floor balcony. At least 10 people were wounded. Sirens sounded for people to assemble in bomb shelters.

Later in the day, seven rockets landed in the ancient Israeli city of Safed, killing an elderly woman and wounding 11 other people, authorities reported. The Israeli military said the 70-year-old woman died of her wounds after a community center for immigrants was struck by a rocket. Safed is 10 miles from the Lebanon border.

The brazen raid Wednesday morning by Hezbollah, a powerful, armed Shiite faction that takes part in the Lebanese government and effectively controls the southern border, created a quandary for Lebanon, Israel and the United States.

The United States called the attack a terrorist act, but officials appeared reluctant to see fighting wreck a country that has emerged as one of the success stories of Bush administration policy in the Middle East.

At a news conference in Germany Thursday morning, Bush said Israel has the right to defend itself and declared that Syria "needs to be held to account" for supporting and harboring Hezbollah.

"If you really want the situation to settle down, the soldiers need to be returned," the president said. "My attitude is this: there are a group of terrorists who want to stop the advance of peace. Those of us who are peace-loving must work together to help the agents of peace."

In a diplomatic effort to defuse the crisis, U.N. Secretary General Kofi Annan is sending a team of negotiators to the Middle East to meet with Arab League foreign ministers in Cairo and leaders in Israel, Lebanon, Syria and the Palestinian territories, a U.N. spokesman announced. The three-person team will urge all parties to "exercise restraint," respect international humanitarian law and do everything possible "to help contain the conflict," the spokesman said.

In Brussels, the European Union criticized the Israeli attacks, saying it was "greatly concerned about the disproportionate use of force by Israel in Lebanon in response to attacks by Hezbollah on Israel." In a statement issued by Finland, which currently holds the EU's rotating presidency, the group also called for the immediate release of the captured Israeli soldiers.

The EU statement said the Israeli air and sea blockade of Lebanon "cannot be justified," and it deplored the loss of civilian lives and the destruction of civilian infrastructure.

In a separate statement, Javier Solana, the EU's foreign policy chief, said he plans to travel to the region on a peace mission.

Israeli Prime Minister Ehud Olmert held Lebanon directly responsible for the ambush and promised a "painful and far-reaching response," a threat that recalled broad Israeli offensives in southern Lebanon in 1993 and 1996.

"We are not at war, but we are in a very high-volume crisis, and we have an intention to put an end to the situation here along the northern border," said Lt. Gen. Dan Halutz, chief of staff of the Israel Defense Forces, according to the wire service reports.

Lebanon's government, in a carefully worded statement, said it had no knowledge of the attack and was not responsible for it. In Lebanon and elsewhere, the attack emboldened Hezbollah's supporters, who greeted the news by handing out sweets and setting off fireworks.

Israel's military response to the attack effectively constituted the opening of a second front for the country, whose troops entered the Gaza Strip last month in search of a soldier seized June 25. Five Israeli soldiers were killed inside Lebanon Wednesday after the army crossed the border in pursuit of the captured soldiers. It was one of the military's highest one-day death tolls in more than four years.

The airstrikes destroyed runways at Beirut Rafiq Hariri International Airport, forcing the closure of the modern, $500-million facility that had been considered an emblem of Lebanon's post-civil war reconstruction.

Bombs also targeted Hezbollah institutions, such as the television station in Beirut's predominantly Shiite southern suburbs; and key infrastructure sites -- roads, bridges and power stations -- in hopes of cutting off supplies to those holding the soldiers, and making it difficult for them to move around undetected.

The upper-floor windows of the five-story television building were blown out, but a blue-and-yellow sign outside that says, "The Channel of Resistance and Liberation/The Channel of Arabs and Muslims," was unharmed. The station -- in the heart of south Beirut -- continued to operate.

A bridge over the Damour River, on the road connecting the coastal city of Sidon to Beirut, was destroyed by a bomb just after midnight. Hundreds of vehicles carrying residents away from the border region and toward the capital found themselves stuck. Traffic backed up for more than a mile.

"Look at this. The way's blocked," said Khaled Barhun, a 40-year-old construction worker from northern Syria who had fled the bombing in Sidon. "All the people want is to feel safe, so they make it here."

By 11 a.m., Lebanese military troops, using bulldozers and trucks, had pushed enough dirt into the river to create a makeshift crossing, and the cars had begin to move.

Hezbollah, meanwhile, said it would continue to fire at targets across northern Israel, utilizing an arsenal of rockets that it said numbers as many as 13,000.

Hezbollah said it captured the Israeli soldiers about 9:05 a.m. Wednesday, when its fighters managed to cross the heavily fortified border near Shtula, an Israeli farming town of about 350 people. Guerrillas fired on two Israeli army vehicles, killing three soldiers and capturing two others.

Hezbollah's leader, Hasan Nasrallah, said an hour passed before Israeli forces set out to recover the captives, giving Hezbollah time to smuggle them to a place he called "safe and far, far, far away." He said the attack had been planned for months and was aimed at forcing negotiations that would win the release of three Lebanese held in Israeli jails.

"Let this be clear, the prisoners will only return home through indirect negotiations and a trade," Nasrallah told reporters at a news conference in southern Beirut, one of Hezbollah's strongholds. "If the Israelis are considering any military action to bring the hostages home, they are delusional, delusional, delusional."

"We don't want an escalation in the south, nor war," he said. "But if the Israelis want an escalation, then we are ready for a confrontation and to its furthest extent. If Israel chooses confrontation, we are ready, and it should expect surprises."

Israeli officials said Wednesday that operations by the military -- known formally as the Israel Defense Forces, or IDF -- could escalate and, at least publicly, they ruled out negotiations on the two soldiers' release.

"The murderous attack this morning was not a terrorist act, it was an act of war," Olmert said in Jerusalem.

Israel also moved deeper into the Gaza Strip on Wednesday, killing 23 Palestinians, most of them civilians, hospital officials in Gaza said.

Early Thursday, an Israeli airstrike destroyed a building housing the Hamas-controlled Palestinian Foreign Ministry, according to the Associated Press. Palestinian medical workers said 13 people in the neighborhood, including six children, were injured. Before daybreak, a fighter from Islamic Jihad was killed and one was wounded in an Israeli airstrike in southern Gaza.

But Israel so far has been unable to find the 19-year-old Israeli corporal who was kidnapped from an army post just outside Gaza almost three weeks ago. It faces even more difficult terrain in southern Lebanon, where Hezbollah draws most of its support.

Wednesday's death toll on the Israel-Lebanon border was the highest for the Israeli military in major fighting since April 9, 2002, when 13 of its soldiers were killed during fighting in the West Bank city of Jenin. Hezbollah said one of its fighters was killed in the fighting as well.

It was the first time Israeli troops had entered Lebanon in force since May 2000, when the military ended its presence on a rocky, hilly swath of southern Lebanon that it had first occupied in 1978.

Hezbollah last captured an Israeli soldier in October 2000, when it seized three who were later executed or died of wounds suffered as they were taken. The bodies of the three soldiers, along with a civilian kidnapped separately, were returned to Israel in 2004 in exchange for the release of hundreds of Palestinian and Lebanese prisoners in Israeli jails.

Four of the Israeli soldiers killed Wednesday died when their tank struck a mine. The eighth soldier was killed trying to retrieve the ruined tank and the remains of his colleagues in the evening, the Israeli army said.

A small contingent of Israeli troops remained inside the Lebanese border as darkness fell, trying to recover the remains of the dead soldiers. Hezbollah broadcast video footage of what was described as the wreckage through the day.

On Lebanon's Mediterranean coast south of Sidon, Israeli warplanes bombed at least five bridges in quick succession on Wednesday, effectively cutting southern Lebanon off from the rest of the country.

Scores of suddenly stranded Lebanese, their faces drawn, wandered back roads looking for a way home. As they walked, carrying bags, ambulances with their sirens blaring passed them in the other direction.

"We're scared, we're scared. From the moment of the attack until now, we're just scared," said Um Fatima, whose cousin, 40-year-old Mohammed Saghir, was one of those killed in an airstrike on a bridge.

On Israel's side of the border, Katyusha rockets fired by Hezbollah fighters landed in sage patches and eucalyptus groves. Small brush fires lit up some of the hills near Shtula, and smoke from smoldering roads and bridges in Lebanon appeared in the near distance, sending a dark smudge tailing south for miles at twilight.

The Israeli residents of agricultural towns and even some of the seaside beach resorts were ordered through loudspeakers into bomb shelters and warned of rocket attacks.

The ambush of Israeli troops seemed likely to bolster the martial reputation of Hezbollah, which probably enjoys more support in the rest of the Arab world than in Lebanon itself, where other sectarian factions have pushed for it to disarm. Nasrallah has vowed on numerous occasions to seize soldiers as a bargaining chip for the Lebanese prisoners; in one speech, he said it would happen this year.

But the broadening of the Israeli response north to Beirut's airport will put additional pressures on Hezbollah, both inside the country and abroad. Some Lebanese officials have already questioned whether Hezbollah had the right to make a decision that could potentially drag the entire country into war.

In southern Lebanon, often a battleground between Hezbollah and Israeli forces, the soldiers' capture was praised; residents said they had grown accustomed to the kind of fighting that has followed.

"Look, we're used to it. For 25 years, 26 years, it's been like this," said Hassan Qaryani, 21, a butcher from Burj Rahal. He stood with a friend, Mohammed Tahine, near a destroyed bridge, looking down at the rubble and tangled iron rods.

He called the kidnapping "like a crown on my head."

"As soon as I heard the news I was overjoyed," he said. "It was like Italy winning the World Cup."

His friend grinned as he looked at the bridge. "If you don't destroy, then you don't build," he said.

Wilson reported from Shtula and Nahariya. Branigin reported from Washington. Staff writer Debbi Wilgoren contributed from Washington. Special correspondents Alia Ibrahim in Beirut, Islam Abdelkareem in Gaza City and Sufian Taha in Jerusalem also contributed to this report.