Updated

Serbia's ultranationalists held a rally on Tuesday to accuse their country's president of treason for agreeing to take part in the first Serbia-Kosovo summit since their war ended in 1999.

The talks between Serbian President Tomislav Nikolic and Kosovo leader Atifete Jahjaga — scheduled to take place in Brussels on Wednesday — are part of an EU-brokered effort to improve ties between the former foes.

The war ended when NATO used a bombing campaign to chase Serbian troops out of Kosovo.

Today the mostly ethnic Albanian province is recognized as an independent country by some 90 countries, including the U.S. and most EU members, even though Russia continues to back Serbia's claim on the territory.

Serbian nationalists still consider Kosovo as the medieval cradle of the Serbian state and the Orthodox religion, and they have pledged never to give it up. But Serbia's government knows it must normalize relations with Kosovo to advance its bid to join the European Union.

On Tuesday, dozens of followers of the extreme nationalist Serbian Radical Party rallied outside the Serbian presidency building in downtown Belgrade, waving flags and anti-EU banners. "Nikolic's decision is clear and obvious treason," said senior party official Nemanja Sarovic.

An elderly man, who identified himself only as Luka, added: "I came here to protest against Kosovo being handed over to the Albanians."

Nikolic is a former ultranationalist who backed the onslaught by Serbian forces on separatists that NATO stopped in Kosovo, but he toned down his rhetoric and proclaimed himself pro-European Union before becoming Serbia's president last year.

In another sign of progress, Serbia's government on Monday night named its first liaison officer to Pristina.