The European Union's top diplomat was holding talks Monday with the leaders of Serbia and Kosovo in Brussels, in a bid to defuse tensions between the Balkan neighbors amid their dispute over vehicle license plates.

The EU's high representative, Josep Borrell, had separate talks planned with Serbian President Aleksandar Vucic and Albin Kurti, the prime minister of Kosovo, before a joint meeting later in the day.

The EU said: "the focus of the emergency meeting will be on finding a way out of the current crisis and avoiding any further escalation and tensions on the ground, with an emphasis on license plates and the return of Kosovo Serbs to Kosovo institutions."

The EU warned Serbia and Kosovo last week that they are on the edge of a precipice and must resolve their dispute or face the prospect of a return to their violent past.

Long-simmering tensions between Serbia and its former province mounted in recent weeks over the Kosovo government’s decision to ban Serbian-issued license plates. On Nov. 5, 10 Serb lawmakers, 10 prosecutors and 576 police officers in Kosovo’s northern Mitrovica region resigned over the move.

Under the ban, about 6,300 ethnic Serbs owning cars with number plates deemed to be illegal in Kosovo were to be warned until Monday's deadline, then fined for the following two months. From April 21, they would only be permitted to drive with temporary local plates.

The issue of Kosovo’s independence sparked a 1998-99 war in which about 13,000 people died. Serbia launched a brutal crackdown to curb a separatist rebellion by the territory’s ethnic Albanians. NATO bombed Serbia in 1999 to end the war.

Kosovo unilaterally broke away from Serbia in 2008. The Serbian government, with support from China and Russia, has refused to acknowledge Kosovo’s statehood. The United States and most of its European allies recognize Kosovo as an independent country.