The leaders of Serbia and Kosovo failed to reach an agreement on longstanding border and mutual recognition issues that have spiked tensions in the Balkans and added to Europe’s instability during the war in Ukraine, the European Union’s foreign policy chief said.

Serbian president Aleksandar Vucic and Kosovo prime minister Albin Kurti held talks in Brussels during a meeting that the EU’s top diplomat said took place “in a crisis management mode”.

Josep Borrell, the EU’s high representative for foreign affairs, announced after the two leaders met: “Today, there is no agreement.”

He said Mr Kurti and Mr Vucic did consent to more discussions on a regular basis to hasten the process of normalising ties between their countries.

Kosovo’s prime minister Albin Kurti
Kosovo’s prime minister Albin Kurti, pictured, met with the Serbian president in Brussels (Olivier Matthys/AP)

There were no immediate comments from Mr Vucic and Mr Kurti. Serbian media said Mr Vucic would “address” his nation on Friday.

Kosovo is a former province of Serbia, which has refused to recognise the country’s 2008 declaration of independence. A Nato-led intervention in 1999 ended a war between Serbian forces and separatists in Kosovo and stopped Belgrade’s bloody crackdown against majority Kosovo Albanians.

The European Union has overseen years of talks to normalise their ties, saying that was one of the main preconditions for Kosovo and Serbia’s eventual membership in the 27-nation bloc.

The purpose of Thursday’s meeting “was to calm down the situation on the ground”, Mr Borrell said.

Tensions between Serbia and Kosovo soared anew late last month when Mr Kurti’s government declared that Serbian identity documents and vehicle licence plates would no longer be valid in Kosovo’s territory.

Minority Serbs, who live mostly in northern Kosovo, reacted with anger, putting up roadblocks, sounding air raid sirens and firing guns into the air and in the direction of Kosovo police officers. No-one was injured.

Under apparent pressure from the West, Mr Kurti postponed the implementation of the measure for a month, to September 1.

“We are at a critical time for Europe,” the EU’s Mr Borrell said.

“After the Russia invasion of Ukraine, we are facing a dramatic and very dangerous moment for our continent, and this is not a moment for increasing tensions.

“It is time for looking for solutions of long-standing issues.”

Along with Serbia, its allies Russia and China do not recognise Kosovo’s independence, which is supported by the United States and most other western states.

There are fears in the West that Russia could encourage Serbia into an armed intervention in northern Kosovo that would further destabilise the Balkans and shift at least some attention from its war in Ukraine.