EU-led talks to settle tensions between Serbia and Kosovo have so far been fruitless.

"Unfortunately, we did not reach an agreement," said EU foreign policy chief Josep Borrell on Thursday after negotiations with Serbian President Aleksandar Vucic and Kosovo's Prime Minister Albin Kurti.

But this is “not the end of the story”.

More talks would take place in the coming days.

"I'm not giving up," Borrell said.

"We have to look for a solution." Borrell had met first with Kurti and then with Vucic before bringing both politicians together as part of the "Belgrade-Pristina dialogue".

This has been managed by the EU Commission since 2011.

The conflict between Serbia and Kosovo has recently intensified because Pristina, in response to corresponding Serbian regulations, wants to demand a temporary residence permit from Serbs entering the country.

In addition, the members of the Serb ethnic group in Kosovo are to replace their Serb license plates with Kosovar ones.

Serbs in northern Kosovo erected barricades to protest these plans.

As a result, Pristina postponed the new regulations until September 1st.

"Illegal Serbian Structures"

Even before the negotiations on Thursday, Vucic had shown little optimism that an agreement could be reached.

"Even if I continue to hope for some form of solution, I remain skeptical," he wrote on Twitter on Wednesday after a meeting with NATO Secretary General Jens Stoltenberg.

Kurti criticized "illegal Serbian structures" "that have turned into criminal gangs" and erected barricades in northern Kosovo.

Stoltenberg said on Wednesday that the NATO-led security forces were ready to intervene if necessary "should stability be threatened".

The troops could also be reinforced if necessary.

Kosovo declared its independence from Serbia in 2008, but Belgrade still regards it as a breakaway territory and does not recognize it as a separate state.

Most of the Serbian population in northern Kosovo remains loyal to the government in Belgrade.

In the late 1990s, 13,000 people were killed in the war that followed Kosovo's struggle for independence

Around a hundred countries around the world now recognize Kosovo as their own country, including most EU countries and the USA.

Serbia's allies China and Russia, on the other hand, refuse to recognize Kosovo.

Both Serbia and Kosovo aspire to join the EU.

Serbia has received candidate status and has been negotiating accession with the EU since 2014.

The EU classifies Kosovo as a "potential candidate".