Greek Cypriots run Cyprus’s internationally recognised government, while Turkish Cypriots have a breakaway state in the north – recognised only by Ankara. The rebel state say resources around the island belong to them too.
After speaking to the Cyprus President Nicos Anastasiades, President of the European Council, Donald Tusk, said: “I call on Turkey to avoid threats or actions against any EU member and instead commit to good neighbourly relations, peaceful dispute settlement and respect for territorial sovereignty.”
The EU Commission echoed Mr Tusks’ warning, saying: “Turkey needs to commit unequivocally to neighbourly relations and avoid any kind of source of friction, threat or action directed against a member state.
“The EU also stresses the need to respect the sovereignty of member states over their territorial sea and airspace.”
This morning Turkish President Tayyip Erdogan called on Cyprus not to “overstep the mark”.
Cyprus is one of several states, including Israel and Lebanon, racing to tap gas deposits in the eastern Mediterranean.
Turkey’s foreign ministry has not made any mention of obstructing the Eni ship, but said the case was a unilateral move by Greek Cypriots that violated the sovereign rights of Turkish Cypriots.
Ankara accused Greek Cypriots of jeopardising security and stability on the ethnically split island and in the region.
But on Monday Greece hit back, saying Turkey had violated international law and said its “provocative conduct” was inconsistent with that of a country seeking accession to the EU.
The foreign ministry in Athens said: “We call on Turkey to desist from further unlawful actions and to comply with its obligations stemming from international law.”
Relations between the EU and Turkey have become strained over human rights allegations following a large-scale by crackdown by Ankara in the wake of a failed Turkish coup in 2016.
However, European countries still rely on Turkey as a NATO ally and as a brake to help reduce an influx of Syrian and other refugees into the bloc.
Turkey’s EU minister, Omer Celik, will join 28 foreign ministers of the bloc for talks in Bulgaria on Friday.
Ankara is pushing to lift visa requirements for its citizens travelling to Europe.
Despite being careful to avoid upsetting President Tayyip Erdogan, EU chiefs are currently unwilling to grant the migration concession.
But Brussels is due to commit more money for the large number of Syrian refugees living in Turkey.