Serb nationalists _ furious over the holding of a NATO conference in Serbia _ have burned a NATO flag and put up a huge banner at a Belgrade bridge denouncing the Western military alliance.

About 200 ultranationalists gathered Monday outside President Boris Tadic's office, chanting anti-NATO slogans and singing Serb nationalist songs.

Dozens scuffled with riot police at similar protests on Sunday.

Nationalists are angry over NATO's bombing in 1999 of Serbia, which ended the country's rule in Kosovo. They spread the banner Monday reading "Never in NATO" along one of the bridges across the Sava river in the Serbian capital.

Pro-Western authorities have stepped up cooperation with NATO, joining Partnership for Peace program for ex-communist nations.