Long columns of Israeli tanks and armored vehicles lumbered into Nablus in the northern West Bank Wednesday night, firing their cannons against Palestinian resistance, while about 40 miles to the south scores of Palestinian gunmen remained holed up inside the Church of the Nativity in Bethlehem's Manger Square.

The massive assault on Nablus, a city of about 100,000 and a focal point of Palestinian militant groups, was the latest step in a methodical, six-day-old military offensive undertaken by Israel to destroy what Prime Minister Ariel Sharon has called the Palestinians' terrorist infrastructure. At the same time, a second front intensified farther north, where gunners from Lebanon's Shiite Muslim Hezbollah movement exchanged artillery and mortar fire for a second day with Israeli troops in a disputed enclave at the intersection of the Israeli, Syrian and Lebanese borders.

Under mounting public pressure, the Egyptian government announced a cutoff of official contacts with Israel, except for diplomatic contacts that could help the Palestinians. The move seemed largely symbolic, but nonetheless was a sign of mounting anger throughout the Arab world over Israel's onslaught against the Palestinians.

U.S. and other efforts to arrange a truce between Israel and the Palestinians, or even to contain the violence, have been eclipsed by the Israeli offensive and a string of deadly Palestinian suicide bombings. Palestinians have set off seven of the bombs over the last seven days, but none was reported Wednesday.

The United States sought Israel's permission earlier this week for its presidential envoy to the Middle East, Anthony C. Zinni, to visit Yasser Arafat, the Palestinian leader, in his besieged compound in the West Bank city of Ramallah. The Israeli defense minister, Binyamin Ben-Eliezer, rejected the request, although Israeli officials said the decision might be reviewed. Zinni has not spoken with Arafat since Saturday.

"The policy of the government is that he will remain in total isolation," said Raanan Gissin, a spokesman for Sharon.

Israel's refusal angered U.S. officials, who are under mounting criticism at home and abroad for having done too little to halt the escalating conflict. "We should be able to see whomever we want to see," said one official, speaking on condition of anonymity.

Sharon convened his key ministers to consider Israel's response to Hezbollah's actions along the border. Syria, a main backer of Hezbollah, redeployed thousands of its troops stationed in Lebanon eastward to positions in the Bekaa Valley that would be less vulnerable to airstrikes. Israeli warplanes struck Hezbollah sites in southern Lebanon Wednesday night but Israel has refrained from attacking Syrian targets.

"Nobody can accept it as routine that every day our outposts [near the Lebanese border] are being attacked for no reason," Ben-Eliezer said.

The United States warned Syria and Lebanon to restrain Hezbollah or risk severe deterioration of the situation.

The standoff at the Church of the Nativity, which is surrounded by Israeli troops, dragged through its second night as the army negotiated for the surrender of what it said were more than 200 gunmen and terrorists inside. "We're trying to find a way to make this have a happy end with no damage to the church," said Lt. Col. Olivier Rafowicz, an army spokesman. "If they would just come out from the church, we'll arrest them if they're connected to terror."

Scores of Christian clergymen, including the Latin patriarch in Jerusalem, Monsignor Michel Sabah, attempted to walk into Bethlehem to mediate an end to the showdown. They were turned back by Israeli troops at the northern entrance of the town.

Israel said an unspecified number of Palestinian militants escaped after having been surrounded in Bethlehem's Santa Maria church and convent, not far from the Church of the Nativity. It was not clear how they got away. Israel insisted its troops would not shoot at the church even if they were fired upon.

"We understand the sensitivity there," said Gideon Meir, a Foreign Ministry official.

Separately, a convoy of armored vehicles from the governments of the United States, Italy, Japan and Britain entered Bethlehem to evacuate peace activists who have been trapped there.

Dozens of Israeli tanks streamed into Nablus, the major Palestinian city in the northern West Bank. They attacked from two directions in what Israeli officials acknowledged was a large-scale operation designed to suppress resistance from Islamic and other Palestinian forces, for whom Nablus is a stronghold. It was not clear whether Israeli forces were also attacking the Balata refugee camp just east of Nablus, another base for militant groups including the al-Aqsa Martyrs Brigades, which sprang from Arafat's Fatah movement.

The al-Aqsa Brigades have carried out many of the suicide bombings and other attacks against Israelis this year. Yet when Israeli forces attacked Balata about a month ago, most of the al-Aqsa militants escaped. This time, Israeli officials say they are determined to arrest or kill Palestinian fighters and other wanted men.

Large Israeli forces also reinforced their reoccupation of Jenin, north of Nablus, and entered Salfit, south of Nablus. In fighting in Jenin and its adjacent refugee camp, one Israeli soldier was killed and several others were slightly injured. Six Palestinians were reported killed, including gunmen and a 30-year-old female doctor.

After six days of their largest military offensive in 18 months of fighting, Israeli forces again control most of the major Palestinian population centers in the West Bank that were returned to Palestinian administration in the mid-1990s -- Nablus, Ramallah, Qalqilyah, Tulkarm, Bethlehem and Jenin -- as well as a number of smaller towns.

Hundreds of tanks and tens of thousands of troops are involved, and Israel appears on a war footing, its citizenry grim and determined. In the West Bank, the Palestinian economy has collapsed, nearly all large-scale commerce and trade is at a halt and the mood is desperate.

"We hate you," said Ahmed Abdel Rahman, a senior Arafat aide who addressed Israelis in an interview with Qatar-based al-Jazeera satellite television. "You should take your tanks and your soldiers and your settlers and get out. The air hates you, the land hates you, the trees hate you, there is no purpose in you staying on this land."

Arafat, confined by Israeli troops to a single floor of his headquarters in Ramallah, continued to strike a defiant note. He told al-Jazeera that he would rather die than be forced into exile as Sharon has proposed.

"Is this his homeland or ours?" the Palestinian leader said. "We are rooted here from before the time of Abraham our prophet." Asked about the possibility of Palestinian surrender, Arafat said: "God forbid! I told you, brother: Martyr, martyr, martyr!"

Nonetheless, there were increasing signs that his eight-year-old Palestinian Authority is crumbling. The Islamic Resistance Movement, known as Hamas, criticized Arafat's security chief in the West Bank, Jibril Rajoub, accusing him of knuckling under to Israeli forces.

About 200 Palestinian militants, security officers and civilians who had been surrounded inside Rajoub's headquarters near Ramallah gave themselves up Tuesday to Israeli troops in a bargain mediated by the CIA. Hamas said Rajoub was guilty of "continuous betrayal" for having authorized the surrender and refusing to allow six Hamas militants in the building to flee when Israeli forces approached the area.

As fighting raged around the West Bank, Israel was generally unified in support of the offensive, partly because of the trauma of the suicide bombings in recent weeks. On Wednesday, a 26th person died from the March 27 suicide bombing at a hotel in the coastal resort of Netanya, the deadliest attack on Israelis since the Palestinian revolt erupted in September 2000.

There have been some expressions of dissent by Israelis and others inside the country, however.

Several groups including Israelis, Palestinians and Europeans gathered Wednesday by the busload at the Al-Aram gate in East Jerusalem, a muddy outpost about three miles south of Ramallah. Despite heavy rain, it was one of the larger demonstrations mustered in recent weeks by Israel's battered peace camp, which has found it difficult to preach tolerance and nonviolence in the face of the suicide bombings and Israeli attacks in the West Bank.

"The increasing violence has been so bad in recent days -- that is what brought so many people out," said Rita Fink, a Jewish woman in her fifties from Jerusalem, who bore a sign reading, "We Refuse To Be Enemies." "What you see is both sides going completely to extremes."

The march was launched by Israeli women's groups, who quietly waved banners calling for peace and reconciliation. But those demonstrators were quickly elbowed aside by militant Palestinians who chanted, "In blood and fire we will redeem Palestine!" and waved posters of Arafat while vilifying Sharon as a war criminal.

"I'm confused," said Sari Nusseibeh, president of Al-Quds University in East Jerusalem and a Palestinian official with close ties to Arafat. "So many people with so many different messages. They've all come to express their dissatisfaction with the state of violence that exists. But different people have different ideas of how to get there, I suppose."

Staff writer Craig Whitlock contributed to this report.

A tank shell explodes in downtown Nablus, a major Palestinian population center in the northern West Bank. Dozens of Israeli tanks entered Nablus in what Israeli officials said was a large-scale operation designed to suppress resistance from Islamic and other Palestinian forces.