BERLIN (Reuters) – Germany’s foreign minister Siegmar Gabriel met his Turkish counterpart Mevlut Cavusoglu in Turkey on Saturday, in a chance to discuss strained ties between the NATO allies after a series of diplomatic incidents.

Gabriel and Cavusoglu discussed “bilateral relationships as well as difficult themes and expectations on both sides” in an informal meeting in the Turkish city of Antalya, the German foreign ministry said on Twitter, without giving further detail.

The meeting came a day after the announcement of the release of a further German national who had been detained in Turkey for political reasons, leaving the tally of those still in jail at nine.

Ties between the two allies deteriorated after Turkish President Recep Erdogan launched a crackdown on political opponents after a failed coup last year. Germany has criticized the mass arrests and refused to extradite people Turkey says were involved in the plot.

Relations with Turkey are a contentious issue in talks on forming a coalition government that Chancellor Angela Merkel’s conservative bloc is holding with two other parties after she lost support in an election in September.