Updated

Hundreds of thousands of people marched on American embassies in world capitals Thursday to protest the war against Iraq, including a violent clash in Cairo, where demonstrators hurled stones and metal barricades and pounded on cars.

Riot police in the Egyptian capital used water cannons to keep about 1,000 stone-throwing demonstrators, mainly students from the American University in Cairo, from reaching the U.S. Embassy.

The protesters began throwing metal barricades when riot squads tried to block them from joining about 500 Muslim Brotherhood and communist anti-war demonstrators about 50 yards from the downtown embassy. Police took swings at demonstrators' heads with batons, but some also were heard to shout: "Don't hit them! Don't hit them!"

Soon, demonstrators broke through and more than 2,000 people were surrounded by riot police. Demonstrators shouted "Down with Arab leaders!" and "Leave, leave Mubarak!" in reference to Egyptian President Hosni Mubarak - an indication of the anger many Arabs feel toward their own governments for failing, in their view, to act strongly enough to avoid war.

By late afternoon, about 5,000 people had regrouped in downtown Cairo's Tahrir Square. As they set out again toward the embassy, police sprayed them with soapy blue water and stone-throwing resumed.

Police also unleashed several police dogs, sending protesters running. There were no reports of dog bites.

Essam el-Eryan, a prominent Muslim Brotherhood member among the protesters, said: "American interests shouldn't feel safe in the Arab region. Iraq should be supported to transform the swift war that the U.S. wants to gang and city fights, to make Iraq a graveyard to the Americans."

"This way, American people will revolt against this war," he said.

As demonstrators scattered, charging through downtown streets, many shops and restaurants closed, including a Hardee's fast-food restaurant. A nearby KFC, however, was open, and demonstrators hadn't damaged any businesses.

Violence also erupted in Manila, Philippines. Police used shields and truncheons to disperse about 300 anti-war activists trying to approach the U.S. Embassy, injuring at least 12 demonstrators, protest leaders said.

Although small in number, anti-war protests at the tightly guarded seaside embassy have become more aggressive and boisterous, and police have responded this week with dispersals and arrests.

Throughout the day, a phalanx of police kept protesters on a road several yards away from the embassy, where they burned a U.S. flag and portraits of President Bush and Philippine leader Gloria Macapagal Arroyo, one of the staunchest Asian allies of the U.S.-led war on terrorism.

More than 100,000 people, many of them high school and university students, marched to the U.S. Embassy in Athens, Greece, chanting "No to the war" and "Americans, killers of people." More demonstrations were planned for Friday and the weekend.

Greece's largest labor union called a three-hour nationwide strike for Friday, followed by a march to the embassy. The governing Socialist Party has called on Greeks to attend the protests and teachers' unions gave students the day off to participate.

The American Community School in Athens was closed for security reasons until March 24. More than 50 children from the U.S. embassy attend the school.

In a related development, a suburban branch of Citibank was slightly damaged by a firebomb, police said. There was no claim of responsibility. Police have increased security at American businesses around Greece.

In Italy, a two-hour nationwide general strike was called for late afternoon.

Earlier, students, labor union members and other protesters marched in several Italian cities. An estimated 45,000 people turned out in Milan. Police in Rome blocked anti-war demonstrators marching up Via Veneto toward the U.S. Embassy, while tens of thousands of students, workers and other Italians blocked highways and train tracks elsewhere.

In Paris, about 10,000 youths protesting the war gathered at the Place de La Concorde beside the heavily guarded U.S. Embassy for an evening demonstration. Earlier, they railed against the "unilateral war of the United States" in eastern Paris.

Some demonstrators shouted "Bush-Blair: Killers!", while others waved banners saying, "Yankee go home."

More than 15,000 protesters marched through Dhaka, Bangladesh, chanting anti-U.S. slogans and burning American and British flags. Bangladesh's leftist forces joined hands with Islamic demonstrators.

Demonstrators also tried to get their points across outside busy capitals. More than 11,000 people marched to the U.S. Consulate in the northern Greek port of Thessaloniki, while 10,000 rallied outside the British Consulate in the western port of Patras.

"We are protesting the attack against Iraq because we cannot accept the cowboy stance of the supposed planet lord," Athens teacher Christos Gotzias said of Bush. "The end result will be the disappearance of the planet lord."