The front of the opposition Democratic Party's office in Belgrade is an imposing stone building set apart in a tree-lined street.

It has been heavily marked with splashes of red paint and someone has written "this is your blood as well" on the wall.

All this damage was done during the night, but at 1100 local time a crowd of around 50 people arrived at the embassy and started breaking bricks off a nearby wall to throw at the building.

Half a dozen policemen stopped them actually breaking in, but I watched a man throw a couple of bricks at the party building in front of the police, who did nothing to stop him.

War crimes call

The leader of the Democratic Party, Zoran Djindjic, infuriated the government a couple of weeks ago by calling in a BBC interview for President Slobodan Milosevic to be put on trial for war crimes.

On Tuesday, in two towns in Serbia controlled by the Democratic Party there were demonstrations calling for young people not to be sent to Kosovo as soldiers.

Today's attack seems pretty clearly to be a response to this by President Milosevic's supporters.