A lawmaker opened a tear gas canister in Kosovo's parliament and protesters hurled stones in the capital on Tuesday ahead of a vote on a deal to demarcate its border with Montenegro as the last hurdle to obtaining visa-free access to the European Union.

There have been violent protests in Kosovo for the last 10 months against reforms including this proposal, which the opposition says is illegal and would lose Kosovo 8,000 hectares of territory.

Local media cited officials as saying parliament may vote on the border deal on Thursday. The opposition has threatened to stop the vote by all means.

Driton Caushi, a member of the largest opposition party, openened the tear gas canister during a meeting of a parliamentary committee. There have been similar acts by other opposition MPs inside parliament in recent months.

"As long as there will be a criminal government in Kosovo that betrays the national interests, no one should hope that opposition resistance will be over," Caushi said as he was handcuffed and led away by police.

Washington and the European Union, who were the biggest supporters of Kosovo's independence, deny Kosovo would lose land as the opposition claims and say the deal with Montenegro is in line with international and local law.

Kosovo is well behind regional neighbours Serbia, Albania, Montenegro, Macedonia and Bosnia, who obtained visa-free access to the EU's border-free Schengen zone in 2010.

But opposition to the border deal has been fierce in Kosovo, a small state of 1.8 million, and tensions have been exacerbated by an EU-brokered accord with Serbia giving more autonomy to Serb-dominated municipalities.

Kosovo declared independence in 2008, nearly a decade after NATO air strikes drove out Serbian security forces accused of killing and expelling ethnic Albanian civilians during a counter-insurgency war. Kosovo's independence is now recognized by more than 110 countries, though not by Serbia.