European Parliament President David Sassoli has called for allowing the Western Balkan states into the European Union, calling enlargement a “positive project for peace and prosperity.”

Enlargement can bring immense benefits both to the region and to Europe as a whole, helping to secure a stable, prosperous and peaceful continent, he told the Funke Mediengruppe on Sunday.

The pace, he said, would depend on the Western Balkan countries’ fulfilment of the accession criteria. “Reforms still need to be completed in every single one of these countries.” But the European Union must also keep its promises and recognize progress, he said.

In addition to Serbia and Montenegro, the Western Balkan countries include Albania, Macedonia, Bosnia-Herzegovina and Kosovo.

The EU is already conducting accession talks with Montenegro and Serbia, while Albania and  Macedonia are official candidates.