Germany's foreign minister says "the ball is in Turkey's court" as the Turkish government and the European Union face off over conditions for Turkish citizens to be granted visa-free travel to Europe.

The visa waiver is one of the incentives offered by the EU for Turkey to stop migrants leaving for Europe and take back those who do arrive. German Foreign Minister Frank-Walter Steinmeier acknowledged Thursday "we have a strong interest in this agreement on migration not collapsing."

Turkey was given conditions to secure the visa waiver. The main obstacle is Ankara's refusal to narrow its definition of "terrorist" and "terrorist act" amid concerns that journalists and political dissenters could be targeted.

Steinmeier said: "If Turkey fulfills its commitments, then I would be for fulfilling our commitments and allowing visa liberalization."