Watch Euronews live stream
Commission chief Ursula von der Leyen warned that the bloc has a "tool box" of restrictive measures that be applied "immediately" if Ankara doesn't engage in "constructive" dialogue over underwater drilling.
Heads of states of France, Greece, Cyprus, Malta, Italy, Spain and Portugal warned Turkey that "unless it ends its unilateral activities", the EU would "develop a list of further restrictive measures".
Ayse Erdogan says the Greek authorities forced her back over the border to Turkey - in contravention of international law - and she has the evidence to prove it.
Brexit, budget, climate, enlargement, Turkey's military incursion in Syria — what the EU leaders decide on the key issues?
A Turkish ship planning to drill for oil and gas close to Cyprus dropped anchor off the island on Monday, sparking tensions with Nicosia and the European Union.