Chancellor Angela Merkel said on Monday that she could see the six Western Balkan states as future members of the EU, for strategic reasons.
"It is in the European Union's very own interests to drive the process forward here," Mrs Merkel said after an online Western Balkans conference.
She hinted at the influence of Russia and China in the region, without naming them.
Mrs Merkel said stronger regional co-operation promoted since 2014 had already achieved initial success, such as a roaming agreement that had just come into force.
The conference was attended by the heads of government of Serbia, Albania, Northern Macedonia, Bosnia-Herzegovina, Montenegro and Kosovo, as well as European Commission President Ursula von der Leyen.
"Our first priority is to accelerate the enlargement agenda across the region and support our Western Balkan partners in their work to deliver on the necessary reforms to advance on their European path," Ms von der Leyen said.
In the video conference, France's President Emmanuel Macron "very clearly" declared his support for the prospect of the six states joining the EU, Mrs Merkel said.
She also said Germany would give 3 million Covid-19 vaccination doses to the Western Balkan nations "as soon as possible".
