A meeting arranged by the EU failed to resolve the ongoing row between Kosovo and Serbia over car license plates Monday.

EU foreign policy chief Josep Borrell hosted Serbian President Aleksandar Vucic and Kosovo Prime Minister Albin Kurti in Brussels amid a row that could trigger a regional crisis.

Afterward, Borrell said Vucic had been ready to accept an EU compromise proposal on vehicle licensing "that could have avoided this risky situation" but that Kurti had not.

He told reporters that he would brief EU member states and allies "about the behavior of the different parties and the lack of respect for international legal obligations.

"And I have to say that, particularly for Kosovo, I know this sends a very negative political signal," he warned.

The underlying source of tension is Kosovo's 2008 declaration of independence which Serbia does not recognize. Belgrade encourages Kosovo's Serb minority to remain loyal to Serbia.

In the latest development this month, Serbs in northern Kosovo resigned from public institutions in protest over the row on vehicle number plates.

Pristina has declared that by next April, around 10,000 Kosovo Serbs with license plates issued by Serbia must replace them with plates from the Republic of Kosovo.

The dispute sounded alarm bells in the European Union, which has been mediating talks to try to normalize ties, and wants both sides to hold off on provocative gestures.

After Monday's latest emergency mediation, Vucic insisted that Serbia had been "absolutely constructive" and had agreed to back a text that had been modified "dozens of times."

"All we did was insist on the fact that the agreements already signed be applied," the Serb leader told TV Pink.

'Irresponsible'

Kurti, however, told reporters that Kosovo was demanding broader talks leading to full normalization of ties.

"We cannot be irresponsible and not deal with pertinent issues and meet as state leaders that only discuss license plates and not discuss normalization of relations," he said.

"That is why we are in the situation we are in."

With the talks at a stalemate, Borrell said he had urged that Kosovo stop implementing its license plate law in "North Kosovo," meaning the main Serb-majority enclave.

And he told Belgrade not to issue new Serb plates to vehicles from Kosovar cities, arguing that a cooling off period would allow time and space for diplomacy to resume

Vucic said that Serbia had agreed to Borrell's suggestion, but warned: "We'll see what the other party will do."

Last month, the United States pressed Kosovo to delay the license plate requirement, arguing that the Western-backed state had been too stubborn.

Washington, which backed Kosovar forces in 1999 as they fought Serbia, said a decision should be delayed to give time for EU-led diplomacy.

In August, Brussels brokered a deal to allow free movement between Kosovo and Serbia, after a series of violent incidents.