DAMASCUS, Syria (AP) _ Hundreds of protesters attacked the U.S. and British embassies today in the Syrian capital. Three demonstrators climbed the U.S. building's walls, hauled down the American flag and burned it, witnesses said.

The protest was part of a larger demonstration involving tens of thousands of Syrians who marched in the city's main downtown streets, protesting the U.S.-British airstrikes on Iraq.

Chanting ``Down with America,'' a crowd estimated at a thousand surrounded the embassy in the upscale al-Rawdha neighborhood in Damascus. Many pelted the building with stones, shattering windows.

``It's very crowded. They are throwing stones,'' said a switchboard operator at the embassy who would not give his name.

Witnesses said the U.S. Embassy's Marine guards fired tear gas to disperse the crowd, but the three protesters managed to enter the grounds, scale the walls of the building and burn the U.S. flag.

Large demonstrations are rare in the Syrian capital, which is under tight security control, and today's marches could not have occurred without government approval.

The protesters also attacked the nearby residence of U.S. Ambassador Ryan Crocker, throwing stones and breaking windows. The ambassador's wife, Christine, was in the building but was not hurt, said a Syrian guard outside who would not give his name.

Witnesses, who spoke on condition of anonymity, said the protesters later tried to turn on the U.S. Cultural Center around a corner about a block away, but Syrian police were trying to block their path.

Other demonstrators surrounded and threw stones at the nearby British Embassy and the British Council, a government institution that sponsors English language classes and cultural programs.

The protesters also overturned a British diplomatic vehicle, said witnesses.

After initially trying to manage the crowds outside the U.S. and British institutions, Syrian police later tried to break up the protests but were still having trouble controlling the situation after about an hour.

``The Americans are trying to make us kneel down and surrender. ... I will not leave before I burn the flag and make my voice heard,'' said Hafizah Abu Tarbous, a protester outside the U.S. Embassy.

The embassy building was believed to be largely empty and closed for the day. Efforts to reach officials at the embassy proved unsuccessful since the operator said no one was available to comment.

Sirens could be heard wailing in the background as the operator spoke. Most of the protesters outside the building apparently were university students or members of the youth organization of the ruling Baath Party.

Tens of thousands of marchers in Damascus carried banners with anti-American slogans and chanted demands for an end to the attacks on Iraq, which have gone on for three nights.

``No to killing and destruction,'' went one chant. ``The Iraqi people will never kneel down,'' was another.

``The Syrian people are with you, our Iraqi brothers,'' read one banner carried by protesters.

During the protest marches, patriotic Syrian songs blared from loudspeakers on some government buildings.

The protests in Damascus were part of a massive show of support for the Iraqis across the Arab world. Demonstrations also erupted today in the West Bank and Egypt, and protests against the U.S. and British attacks were staged Friday in Jordan, Lebanon and Yemen.