Merkel wants to stop Turkey's EU membership talks

German Chancellor Angela Merkel announced her intention to seek an end to EU membership talks with Turkey during her sole face-to-face TV showdown with challenger Martin Schulz on Sunday, putting ties with Ankara centre-stage in Germany's election campaign.

In a sharp escalation of an already intensifying diplomatic crisis between two NATO allies with longstanding historical links, Merkel said: "It is clear that Turkey should not become a member of the European Union."

She said she will discuss with EU counterparts to see if "we can end these membership talks", adding that "I don't see (Turkey) ever joining and I had never believed that it would happen."

Germany will also look at imposing "real restrictions on economic contact" with Turkey, as well as possibly issuing a tougher travel warning against travel to the country, she said.

Merkel's tough line comes after Ankara arrested two more German nationals for "political reasons", according to Berlin.

The plunge in bilateral relations began after Germany sharply criticised Ankara over the crackdown that followed last year's failed coup attempt there.

The escalating tensions have split the Turkish community in Europe's top economy, the largest Turkish diaspora abroad, which is a legacy of Germany's "guest worker" programme of the 1960s and 70s.