Serbian protesters broke into and set fire to the US embassy in Belgrade during a rally against Kosovo's declaration of independence on February 21 2008, Reuters reported.

One protester ripped the US flag off its pole and briefly put up a Serbian flag in its place, while others jumped on the embassy balcony, holding up a Serbian flag, to the cheers of about 1,000 people, the agency said.

Intruders were driven away by riot police, which beat and arrested an unidentified number of people. Thirty people were injured, half of them policemen, Dusan Jovanovic of Belgrade's Emergency Hospital told B92 TV, as quoted by Bloomberg.

The US State Department urged the government of Serbia to protect the embassy, which held only security personnel and Marines at the time of the protest, Bloomberg said.

The embassies of US and Slovenia, which now holds the rotating European Union presidency, have been the target of attacks in recent days, following Kosovo's unilateral declaration of independence from Serbia on February 17.

An estimated 200 000 people attended the government-sponsored rally against Kosovo's independence in Belgrade, which stayed largely peaceful.

"As long as we live, Kosovo is Serbia," Reuters quoted prime minister Vojislav Kostunica as saying during his address, which was met with chants of "We'll never give up Kosovo, never!"