Germany and the European Commission on Thursday called on Serbia and Kosovo to "speed up" the normalisation of their relationship, during a summit with West Balkan states hosted by Berlin.
"It is high time to overcome regional conflicts that have continued for far too long," German Chancellor Olaf Scholz said at the opening of the conference.
"The normalisation process between Serbia and Kosovo in particular must speed up," Scholz said.
The Russian invasion of Ukraine earlier this year added a "sense of urgency" to talks, he added.
Serbia has been a candidate to join the European Union since 2012 but its prospects are seen as bleak while its relationship with Kosovo remains an issue. Belgrade does not accept majority-Albanian Kosovo's 2008 declaration of independence.
Tensions have been exacerbated by the war in Ukraine, with many Serbs sympathetic to traditional ally Russia.
Germany and France have been brokering an agreement to resolve the long-running conflict between the two countries, the details of which have been closely guarded.
Paris and Berlin along with the European Commission were speaking "very actively" with the two Balkan states, Scholz said at the conclusion of the summit.
"Hopefully we will see results soon," he said.
"We call on both sides to move forward," EU Commission President Ursula von der Leyen said at the same news conference.
"This is a bridge that is being built to solve a problem that can be solved," she said.
"After presenting our ideas, we came back from the region with a sense of cautious optimism," a German government source said this week ahead of the summit.
"There is still work to do... the proposal demands pragmatism and a readiness to compromise from both sides," the source said.
Berlin has also warned Serbia against cultivating deeper ties with Russia, which could have "consequences" for its bid to join the European Union, according to the source.
Thursday's summit in Berlin brought together the heads of government of Albania, Bosnia and Herzegovina, Kosovo, North Macedonia, Montenegro and Serbia as well as EU leaders.
Participants from the Western Balkans signed three accords: on mutual recognition of identity documents, university degrees and professional credentials.
