Hundreds of ethnic Serbs on Monday blocked roads in Kosovo's north leading to its only two border crossings with Serbia to protest Pristina's ban on entry of cars with Serbian registration plates.
The row erupted over Kosovo's use of plates with RKS (Republic of Kosovo) on them, which implies its status as an independent nation, something bitterly disputed by Serbia.
Until now, vehicles with Serbian registration plates have been entering Kosovo freely.
But since Serbia refuses to allow cars with RKS plates, demanding that they take temporary plates on arrival, Pristina says its ban is just a reciprocal measure.
Protesters used trucks and cars to completely shut down traffic on the roads towards the Jarinje and Brnjak crossings, an AFP journalist noted. They also set up tents, saying they would spend the night on the barricades.
The Kosovo government on Sunday sent armoured vehicles and a special police unit to the mainly ethnic-Serb area to monitor the implementation of the ban.
"Pristina demonstrates force and nothing else," one of about 500 protesters gathered near the Jarinje crossing told AFP.
The police "will have to leave, if not, it won't be good," said the protester who requested to remain anonymous. "They have no business being in the north."
- US calls for restraint -
"It was not our wish but imposed by the other side," Kosovo Prime Minister Albin Kurti told lawmakers Monday.
Drivers entering Kosovo from Serbia with Serbian registration plates will have to take temporary ones as long as the same rule applies to Kosovo nationals with RKS plates entering Serbia, he added.
Goran Rakic, the only Serb minister in the Kosovo government, joined the protesters on Monday, calling on Pristina to "quit provocations".
Serbs expected Serbian President Aleksandar Vucic to "react and help us, as he has always done so far", he added.
Vucic said he would call for help from NATO if Pristina continued to "endanger Serb property and lives".
He had called a meeting of security officials for Tuesday do discuss the situation in Kosovo, he added.
"I hope we won't be forced to implement our own measures, both economic and political ones," Vucic told a televised press conference.
The US embassy called on both Kosovo and Serbia to "exercise restraint, refrain from further unilateral actions, and reduce tensions -- immediately, without delay", in a message posted on Twitter.
Kosovo proclaimed independence from Serbia in 2008 a decade after the war between Belgrade forces and ethnic Albanian guerillas.
Serbia and Kosovo Serbs still do not recognise the move.
Kosovo and Serbia are conducting EU-sponsored talks on normalisation of ties for a decade.