Biden arrives in Serbia next week as part of a Balkan tour that also includes visits to Bosnia and Kosovo. He is expected to meet with local political leaders and U.S. military and other personnel stationed in the region.

The tour is widely seen in Serbia as an important sign of continued U.S. support for the stabilization of the Balkans, which was embroiled in a series of ethnic conflicts during the 1990s.

But many in Serbia still view the U.S. as anti-Serb because of Washington's support for Kosovo's statehood. The former Serbian province declared independence last year.

The U.S. also led a NATO bombing campaign in 1999 that ended Belgrade's crackdown against the separatists in Kosovo, and Serbia's rule in the region.

Several nationalist parties handed a list of alleged Biden statements to the Foreign Ministry and accused him of supporting the 1999 NATO bombing.

"We believe that the statements and policies of Joseph Biden are contrary to the interests of Serbia and the Serbian people," said Jovan Palalic, of the Serbian Democratic Party.

Another politician, Aleksandar Vulin, added that Biden "is not welcome in Serbia."

The U.S. Embassy did not immediately comment on the nationalists' statements about Biden.

In February 2008, nationalists rioted because of their anger over U.S. recognition of Kosovo and set parts of the U.S. Embassy on fire. One person died in the unrest.

Serbian Interior Minister Ivica Dacic said Thursday authorities were boosting security measures to the highest level for Biden's visit.