Police said between 15,000 and 20,000 people gathered in front of the US embassy, which has been the site of several small-scale protests since war broke out on March 20.

Protesters carried banners reading: "Stop American agression", "No to World War III", and "Bush must respect Russia."

Many classes were cancelled so students could join the anti-war march, which was the first organized by pro-Kremlin party Russia Unity.

"They let us out of class, so I came along to see why," said Ana Kodyaeva, who admitted she tagged along mostly out of curiousity.

Other protesters said they joined the march to protest US aggression against Russian interests, after a convoy carrying Russian diplomats and journalists was caught in a crossfire between US and Iraqi troops on Sunday.

"It's arbitrary and total disorder," said Dmitry Barinov. "Our diplomats were the target of shooting, one of our journalists was killed. We must do something."

A Ukrainian cameraman for British news agency Reuters was killed Tuesday, along with a Spanish cameraman, when a US tank shot at the Palestine Hotel in Baghdad, where most foreign journalists are staying.

Some 2,300 police and soldiers were deployed to monitor the protest and all traffic in front of the embassy -- on a major thoroughfare in central Moscow -- was halted for several hours.

"Americans -- you belong to international courts and it's time to judge those who gave the order to kill diplomats and journalists," said Alexander Isayev, deputy chief of Moscow's main union federation.

"September 11 was a tragedy for the American people, but President Bush drew no conclusions from it. America presents itself as a 'scarecrow' to scare of terrorism, but it is developing in the world and becoming a means for small countries to defend their right to exist," Russia Unity's deputy chief Andrei Metelsky said.

The protestors adopted a resolution calling for an end to the "unpunished aggression" in Iraq and called on the United States to recognize that "the international organization is the UN and not the Pentagon."

While hundreds of thousands of people demonstrated in cities around the world during the beginning of the US-led military operation in Iraq, no such protests took place in Russia, despite overwhelming opposition to the war.

Previous protests in Moscow, which have never attracted more than a few hundred people, were organized by ultranationalist or communist parties.

The Russian administration has been one of the most outspoken opponents of the US-led war and a poll published in late March found that just 13 percent of Russians hoped the US-led coalition would succeed in its efforts to oust Iraqi President Saddam Hussein.

SPACE.WIRE