Turkish Prime Minister Binali Yildirim said Saturday a phone call with German Chancellor Angela Merkel was "productive", after the nations clashed over rallies cancelled in Germany ahead of an upcoming vote in Turkey.

"Our conversation was good and productive," Yildirim told reporters, adding that German and Turkish foreign ministers would meet next week to discuss the issue.

In the runup to Turkey's referendum on boosting the president's powers, controversy has flared over Turkish politicians' trips to Germany to campaign for a "Yes" vote.