CAIRO, AUG. 11 -- The first contingent of Egyptian troops, part of an Arab force to defend Saudi Arabia from Iraqi attack, arrived today in the oil-producing kingdom, and Egyptian President Hosni Mubarak said he thought there was no hope of a peaceful solution to the crisis over Iraq's invasion of Kuwait.

"I'm always optimistic, but frankly I tell you there is no hope. I wish there was," Mubarak told reporters without explaining the basis for his pessimism.

In what was possibly the first skirmish between opposing Arab forces since the invasion, Saudi antiaircraft batteries today fired about 10 rounds at two Iraqi reconnaissance planes in the Khafji region close to the Saudi-Kuwaiti border, according to diplomatic sources cited by the Associated Press in Riyadh, Saudi Arabia. The sources said the planes turned back without crossing the border.

An Iraqi spokesman quoted by Baghdad radio called the report "some sort of prattle and bufoonery." A Saudi official also denied that the incident took place, and U.S. sources could not immediately confirm the report.

Also today, 11 Americans, including 10-year-old Penelope Nabokov of Albany, Calif., crossed into Jordan after being held up at the Iraqi border for two days. The evacuees included staff of the U.S. Embassy in Baghdad and their dependents. Hundreds of thousands of foreigners remain stuck in Iraq and Kuwait.

Mubarak's pessimistic appraisal of developments in the Middle East came a day after he led an Arab summit to approve a resolution calling for a joint Arab force to help defend Saudi Arabia and other Persian Gulf states from Iraq.

Returning to Cairo from Alexandria, Egypt, where he held talks today with the leaders of Algeria, Syria and Libya, Mubarak remarked to reporters: "I would have done the impossible to open doors for a solution." But he said that during the summit he had rejected a Yemeni proposal to fly to Baghdad with five other Arab leaders to meet with Iraqi President Saddam Hussein because he "knew the result in advance."

Egyptian officials have refused to disclose how many Egyptian troops have been sent to Saudi Arabia, but diplomatic sources said they expect the Egyptian contingent to number several thousand. Moroccan and Syrian contingents, also numbering several thousand each, are scheduled to take up positions in Saudi Arabia as well.

The diplomatic sources said the Egyptian troops arrived at the Hafar Batin Air Base in northeastern Saudi Arabia, about 80 miles west of the Kuwaiti border. Thousands of U.S. troops already have arrived at that base to set up a protective perimeter for U.S. warplanes based there. It was not known how the Arab troops would be deployed.

While neither Mubarak nor any of his senior aides would elaborate on what had made the president so pessimistic, Tahseen Bashir, an Egyptian diplomat and commentator who is widely regarded as an unofficial spokesman for the government, tonight said that Mubarak is under extreme pressure because of the volatility of the crisis at the moment.

Bashir said that the summit's simple-majority approval of the Arab force, although a landmark breakthrough, may turn out to be the easiest hurdle for the Arab leaders to overcome in their efforts to resolve the crisis peacefully.

Referring to the Western and Arab armed forces converging on the Saudi-Kuwaiti border and a multinational flotilla that has the growing appearance of a naval blockade, Bashir said: "It's a question of tightening the noose but not choking it too much. That is not easy."

Bashir, in a telephone interview, said that in their summit Friday the Arab leaders had cast aside normal Arab League voting procedures, which otherwise would have made approval of the Arab military force impossible. Even at that, he said, the Arab League may have been riven so deeply that it may not recover without fundamental restructuring.

He said the fragile support for the summit's resolution and the precarious state in which the Arab League was left as a result of the debate raised questions about what the Arab nations would do if the crisis turned into a shooting war.

"It was easy to take a decision by 12 people and then go home," Bashir said. "But once one bullet is fired, we will face the severity of the task before us."

As the Egyptian president issued his gloomy forecast, Iraq denounced moderate Arab leaders through its official media, calling them "evil men" whose thrones would shake for sending troops to back U.S. forces in Saudi Arabia.

On Friday, Saddam called on the "Arab masses" in Egypt to overthrow Mubarak for allowing U.S. warships through the Suez Canal and permitting overflights by American military aircraft.

Egyptian shipping officials today rejected Iraq's call to close the canal to foreign warships, saying it would stay open in peacetime and war.

"No one but Egypt has the right to stop military vessels from passing through the Suez Canal," Reuter quoted a shipping official as saying.

Meanwhile, a British frigate, the HMS Jupiter, arrived in the Persian Gulf region and a squadron of British Tornado fighter planes landed in Saudi Arabia to join U.S. soldiers and aircraft there.Twelve British Jaguar warplanes were reported headed for Oman.

Italy said the European Community would offer economic aid to Jordan next week to help King Hussein stand up to Iraqi pressure over the gulf crisis.

Italian Foreign Minister Gianni de Michelis, president of the EC Council of Ministers, said the aid would be offered in hopes of rallying Arab moderates against Iraq's invasion of Kuwait but that assistance to Jordan would also be linked to a new bid to solve the Palestinian problem.

"Jordan's position {on the gulf crisis} is luckily evolving in the right direction. We must support this evolution by providing political support, being willing to cooperate economically and showing strong solidarity," de Michelis said.

Jordan, which has had close military and economic ties to Iraq, expressed reservations about Friday's Arab League summit resolution but did not oppose it.

Earlier, Hussein had publicly expressed understanding for Iraq's motives in invading Kuwait and had criticized the Arab League foreign ministers' condemnation of the attack as "premature."

In an interview with Cable News Network, King Hussein made clear today that he would not send troops to Saudi Arabia. Pointing out that the decision by the majority of Arab nations "was not binding on all," he said, "We would have sent Arab troops, together with other Arab troops, if it were to replace a foreign presence in Saudi Arabia."

West German Foreign Minister Hans-Dietrich Genscher reportedly proposed the aid to Jordan at Friday's emergency EC meeting in Brussels, saying the kingdom was in a serious economic crisis.

Today's troop deployments set off another demonstration in Sanaa, the capital of Yemen, where thousands of people rallied in front of the U.S., Egyptian and Saudi embassies in support of Iraq.

Hundreds of Palestinians in the Israeli-occupied West Bank and Gaza Strip were reported to have demonstrated in favor of the Iraqi president, shouting: "Oh Saddam, burn the traitor rulers. With soul and blood we redeem Saddam!"

In the Jordanian town of Irbid as well as in the predominantly Palestinian town of Nusseibeh near Amman, protesters denounced the United States and hailed the Iraqi annexation of Kuwait.

In Beirut, a leader of the pro-Iranian Hezbollah (Party of God) called for suicide attacks in response to the "evil deployment" of Western troops in the gulf. But he said revenge against foreign hostages held in Lebanon would be wrong.

"I think Moslems in Lebanon and the region will be able to face the evil Western deployment in the gulf without venting their anger on the hostages," Hussein Mussawi told Reuter.