Kosovo's opposition has used tear gas to disrupt a parliament vote on a border demarcation deal with Montenegro.
Politicians had to be evacuated from the assembly building in the capital Pristina after the Self-Determination Movement party used tear gas in the hall where the vote was due to start.
The opposition used tear gas again when the session resumed.
The 120-seat parliament was expected to vote to ratify the 2015 deal, which was set as a precondition by the European Union for Kosovo's citizens to freely travel within its visa-free travel zone known as Schengen.
The opposition party says the border deal would mean Kosovo loses 8,200 hectares (20,000 acres) of its territory.
The previous government and international experts deny that claim.
Opposition politician Albulena Haxhiu said they were determined to stop parliament passing the deal.
The collapse of votes for the border demarcation agreement and another proposal seeking to give more rights to the ethnic Serb minority toppled the previous government and took the country to early elections last year.
Prime minister Ramush Haradinaj said before the start of the session they had the votes to pass the deal.
But a parliament majority cannot be secured unless enough votes are gathered from the opposition ranks.
The ethnic Serb community's Serb List party, with 10 seats, was not present in the hall.
"Violence as a political tool has no place in Kosovo. I urge MPs to reconvene and finish the vote today," US ambassador to Pristina Greg Delawie, who was present at the building, wrote on Twitter.
EU ambassador to Pristina Nataliya Apostolova said she was "appalled ... shocked that members of a parliament in Europe are resorting to dangerous tactics".
Ms Apostolova said she contacted opposition leader Albin Kurti and called on all politicians "to defeat such unacceptable practices that go against democratic society and the future of the Kosovo people. MPs, vote for the future, not for the past!"
The opposition party, now divided in two groups due to internal frictions, has used tear gas and similar tactics to disrupt parliament in the past three years.
Montenegro, which has approved the deal, recognises Kosovo's 2008 independence from Serbia, which Belgrade still rejects.