BELGRADE, Serbia (AP) — Hundreds of Serbian nationalists rallied in Belgrade on Wednesday, demanding that President Aleksandar Vucic rejects a Western plan to normalize ties with breakaway Kosovo and pulls out of negotiations.

Shouting “Treason” and carrying banners reading “No surrender,” the right-wing protesters blocked traffic as they gathered near the Serbian presidency building in central Belgrade. The protesters are also strongly pro-Russian, and one banner read: “Betrayal of Kosovo is betrayal of Russia!”

Serbian media reported that one group pushed though metal fences toward the entrance at the end of the rally but was prevented by riot police from reaching the door.

The protest comes amid efforts by U.S. and European Union officials to mediate a solution for the long-standing dispute between Serbia and Kosovo, a former Serbian province whose 2008 declaration of independence Belgrade does not recognize.

Serbia has relied on Russia and China in its refusal to acknowledge Kosovo’s independence, which is backed by Washington and most EU countries. Western officials fear Russia could use simmering tensions in Kosovo to try to destabilize the Balkans and avert some attention from the invasion of Ukraine.

Serbia’s populist president Vucic has said he was ready to consider the Western plan. Its provisions have not been published but it reportedly stipulates that Serbia would not object to Kosovo’s membership in international institutions, including the United Nations.

In Kosovo’s capital Pristina late Wednesday, scores of students protested peacefully against aspects of the proposed agreement with Serbia.

In Serbia, pro-Russian right-wing groups have demanded that Belgrade stop all negotiations over Kosovo and publish the Western plan. Vucic has said this would mean the end of Serbia’s integration into the EU and the country’s international isolation.

Serbia formally seeks EU entry but Vucic has also nurtured close ties with Moscow. Serbia remains the only country in Europe that has not joined sanctions against Russia, though it has condemned the invasion.

Kosovo declared independence after a war in 1998-99 that killed around 13,000 people. Following an armed uprising by ethnic Albanian separatists, Serbia responded with a brutal crackdown that ended after a NATO bombing campaign.

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