NATO Secretary General Anders Fogh Rasmussen is due to visit Kosovo today amid rising tensions.
Ethnic Serbs in the north of Kosovo oppose plans by Kosovo's mainly ethnic Albanian leaders to man two border crossings there.
Serbian President Boris Tadic has warned the plan could spark violence. The country has also sent an official complaint to UN Secretary General Ban Ki-moon.
For his part, Kosovo's Prime Minister, Hashim Thaci, has accused the Serbs of preparing to use violence to block the move.
He also said the plan would go ahead on September 16 with the help of the European Union police force in Kosovo, EULEX, and NATO peacekeepers.
A statement by the head of EULEX, Xavier bout de Marnhac, said "operational work" at the border crossings "will be done by EULEX."
On September 14, Serbs in the north were reported to have halted a convoy of German NATO soldiers heading north to the border.
Serbs in the divided town of Mitrovica set up barricades of buses, rocks and trucks loaded with stones.
Kosovo tried in July to station police and customs officials at the two crossings with Serbia.
Serbs responded by setting up roadblocks and stopped NATO peacekeepers from reaching bases in the north.
With backing from the West, Kosovo unilaterally declared independence from Serbia in 2008. Today, more than 80 countries recognize it as an independent country.
Serbia is under pressure from the EU to work out its problems with Pristina if it wants to gain EU candidate status.
compiled from agency reports