Police fired tear gas Monday at thousands of angry pro-Serb Montenegrins who pelted state buildings with rocks and flares to protest their government's recognition of Kosovo's independence. At least 22 were injured.

The protesters chanted “Treason! Treason!” and “Kosovo is Serbia!” to condemn the government's decision last week to recognize Kosovo, the former Serbian province that declared independence in February.

A dozen protesters and 10 policemen were injured during the running clashes in downtown Podgorica, Montenegro's capital, hospital officials said. Police said 28 demonstrators were arrested.

Earlier, around 10,000 protesters gave the country's pro-Western government until Wednesday to withdraw its recognition of Kosovo, or they would try to topple it “by unparliamentary means.”

“This is the biggest shame in Montenegrin history,” Andrija Mandic, a leader of the pro-Serbian opposition in the parliament, told a rally in downtown Podgorica.

He and other pro-Serbian officials demanded a referendum on Kosovo's recognition. About 35 percent of Montenegro's population of 650,000 declare themselves as Serbs.

After Montenegro and Macedonia, Serbia's neighbors, recognized Kosovo on Thursday, Belgrade expelled the two Balkan countries' ambassadors and threatened additional retaliatory measures – raising tensions in the Balkans.

Serbia, Montenegro and Macedonia were once all part of Yugoslavia. Montenegro, considered Serbia's closest ally, did not split from Serbia until 2006.

On Monday, Prime Minister Milo Djukanovic of Montenegro accused Serbia of wanting to continue to influence his small country's policies.

Belgrade “is forgetting that we are now a sovereign country which is making the decisions in its own interest,” Djukanovic said.

He denied that Montenegro has been under pressure from the U.S. and some EU countries to recognize Kosovo.

Serbia recently won a diplomatic struggle, with the U.N. General Assembly agreeing to ask the International Court of Justice for an opinion on the legality of Kosovo's declaration of independence.