Speaking in Athens after meeting his Greek counterpart, Nikos Dendias, Maas said Turkey’s actions could have consequences for its relations with the EU.

“International law must be upheld. For that reason, progress in EU-Turkish relations is only possible if Ankara halts its provocation in the Eastern Mediterranean,” Maas said.

He added that it was however essential to maintain an honest and open dialogue with Turkey as a strategically important country.

Maas did not address the option of further sanctions on Turkey, which like Germany and Greece is a member of NATO.

Athens and Ankara have long been at loggerheads over Turkish exploratory gas drills in the Mediterranean.

Greece has also complained against Turkish military jets infringing its airspace and accused Turkey of instrumentalizing the refugee crisis.

Cyprus and France have also called for the EU to take a tougher stance on Turkey, with Cyprus accusing it of illegal gas prospecting off its coast.

At the end of February, the EU imposed what it termed “restrictive measures” on two people “in relation to Turkey’s unauthorised drilling activities in the eastern Mediterranean.”