The European Commission's president on Wednesday warned Turkey against trying to intimidate Greece and Cyprus, as tensions grow over energy reserves in the eastern Mediterranean.
In her annual State of the EU speech, Ursula von der Leyen said Ankara was a key partner doing important work hosting refugees but stressed "none of this is justification for attempts to intimidate its neighbours".
Turkey, Greece and Cyprus have been locked in a row over energy resources and maritime borders in the region, with Ankara infuriating the EU countries by sending research ships with naval escorts to work in contested waters.
There have been fears of conflict erupting and Cyprus is pressing the rest of the EU to impose fresh sanctions on Ankara over the drilling.
"Turkey is and will always be an important neighbour, but while we are close together on the map, the distance between us appears to be growing," von der Leyen told the European Parliament.
"Yes, Turkey is in a troubled neighbourhood. And yes, it is hosting millions of refugees, for which we support them with considerable funding. But none of this is justification for attempts to intimidate its neighbours."
Greece and Cyprus can count on Europe's "full solidarity on protecting their legitimate sovereignty rights", she added.