Turkey has been threatened with sanctions by the EU if it continues “illegal drilling” in waters near Cyprus in the eastern Mediterranean.

The warning came at an EU summit in Brussels.

EU Commission President Jean-Claude Juncker called Turkey’s actions “totally unacceptable”.

On June 20, Turkey launched the Yavuz, a second drilling ship for natural gas and oil prospecting off Cyprus.

The Republic of Cyprus is an EU member, but the breakaway north is pro-Turkey.

The European Council called on Turkey to “show restraint, respect the sovereign rights of Cyprus and refrain from any such actions”.

The statement said: “The European Council endorses the invitation to the [EU] Commission and the EEAS [EU foreign affairs service] to submit options for appropriate measures without delay, including targeted measures.”

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The self-declared Turkish Republic of Northern Cyprus is recognized only by Turkey, and is internationally isolated.

Turkey said it was drilling inside its continental shelf, complying with international law.

A Turkish drilling ship, the Fatih, had been anchored west of Cyprus since early May and had begun drilling, the Reuters reported.

Turkey is a candidate for EU membership but its negotiations are currently frozen. The EU Commission has said President Recep Tayyip Erdogan’s government has backtracked on pledges to improve justice and the rule of law. The Turkish government has purged state institutions since an abortive coup attempt against Recep Tayyip Erdogan in July 2016.

Greek PM Alexis Tsipras said the threatened EU measures “are against companies and individuals, a possible EU accession process freeze and measures with significant economic consequences”.

He said at Brussels summit: “These will take place unless Turkey stops its illegal operations inside the Exclusive Economic Zone of Cyprus.”

Turkey – a key NATO partner for the West – has extensive trade ties with the EU and has not yet been hit with EU sanctions, unlike Russia.

The US has also threatened Turkey with sanctions if President Erdogan goes ahead with a deal to buy S-400 air defense missiles from Russia.