Riot police fought running battles with protesters hurling rocks and petrol bombs in Kosovo's capital Pristina on Tuesday in the worst unrest since the former Serbian province seceded in 2008.

Triggered by remarks by an ethnic Serb cabinet minister and a row over a disputed mine, the violence was a potent reminder of the depth of popular dissatisfaction in majority-Albanian Kosovo, still mired in poverty and corruption seven years since declaring independence from Serbia.

A Reuters reporter saw masked police officers firing tear gas and water cannon, trying to disperse about 2,000 protesters who had joined rallies organised by opposition political parties. Protesters also set rubbish containers alight.

Ambulances attended to injured people as police pursued protesters into side streets around central Pristina. Police said 56 police officers were injured, two of them seriously.

It was not immediately known how many protesters were hurt. More than 120 were arrested. Police said they used rubber bullets to disperse crowds.

Kosovo Prime Minister Isa Mustafa, barely six weeks in office, accused his opponents of trying to seize power by force.

"All these political parties have accepted the election results," he said. "They must respect the vote of the citizens and not attempt to take power through violence."

Tear gas and smoke hung in the air after six hours of violence that only subsided as dusk fell.

CLIMBDOWN

It was the second bout of unrest since Saturday, set off by popular anger over a government climbdown over the fate of a huge mining complex claimed by Serbia and remarks deemed offensive by an ethnic Serb minister.

Mustafa's government had pledged to take control of the Trepca mine, which has been held in trust by a United Nations-created privatisation body since Kosovo's 1998-99 war and threatened by myriad creditor claims.

But he backed down days later in the face of a furious response from Serbia, which claims 75 percent ownership of the the complex, and pressure from Western embassies concerned at the possible repercussions for a fragile European Union-led dialogue between the two sides.

Trepca's lead, zinc and silver mines once accounted for 75 percent of the mineral wealth of socialist Yugoslavia, employing 20,000 people. Trepca now operates at a minimum level to keep the mines alive, with several thousand miners from both sides of Kosovo's Serb-Albanian divide.

The protesters also clamoured for the dismissal of an ethnic Serb minister in the mainly Kosovo Albanian government after he branded as "savages" a group of Albanians who lost relatives in the war and had protested against ethnic Serb pilgrims marking Orthodox Christmas in January.

There was no sign of intervention on Tuesday by NATO's 5,000-strong peacekeeping force or hundreds of EU police officers stationed in Kosovo to encourage the rule of law.

Kosovo broke away from Serbia in 1999 with the help of NATO air strikes to halt the killing and expulsion of ethnic Albanians by Serbian forces waging a counter-insurgency war.

The territory of 1.8 million people, 90 percent of them ethnic Albanians, declared independence in 2008 and has been recognised by more than 100 countries.