By Nick Hawton
BBC News, Belgrade
Police in Serbia have arrested 27 people at a gathering of volunteers who pledged to fight to stop the province of Kosovo becoming independent.
Many volunteers were wearing military uniforms
Some 200 volunteers gathered in the town of Krusevac to form a paramilitary unit to oppose any attempt to let the province break away from Serbia.
The UN is currently discussing the long-term future of Kosovo.
Its majority Albanian population want independence. Serbia sees Kosovo as its religious and cultural homeland.
The volunteers, many of whom are veterans from the wars of the 1990s, gathered outside a church in Krusevac, south of Belgrade, to formally create the Guard of Prince Lazar - named after a famous Serb leader who fought in Kosovo more than 500 years ago.
Many were wearing military uniforms and nationalistic symbols, reminiscent of the Serb paramilitary units that operated in Bosnia and Croatia during the 1990s.
Some carried pictures of the indicted war criminal Ratko Mladic.
Police detained 27 people for wearing shirts emblazoned with symbols of the notorious and now disbanded Red Berets special police unit.
One of the organisers, Zeljko Vasiljevic, who is a deputy in the Serb parliament, said the unit would be ready to go into Kosovo and fight to prevent it becoming independent.