Turkey-Greece tensions escalate over Turkish Med drilling plans

Greece has issued a naval alert after Turkey announced it was sending a ship to carry out a drilling survey in waters close to a Greek island off Turkey's south coast.

Turkey's initial advisory on Tuesday sparked alarm in Greece amid reports that naval ships from both countries were preparing to patrol the area.

The EU said Turkey's alert was "not helpful and sends the wrong message".

Turkey said its survey ship was working entirely within its continental shelf.

How have relations soured?

Although the Turkish survey ship, Oruc Reis, was still reported to be at anchor in the Turkish port of Antalya on Wednesday, the Turkish alert - known as a Navtex - prompted alarm in the Greek military and was condemned by Athens as illegal.

The survey alert covers an area between Cyprus and Crete. Unconfirmed Greek reports said Turkish and Greek navy ships were heading to an area near the Greek island of Kastellorizo, a short distance from the Turkish mainland.

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Relations between Greece and Turkey have been icy anyway. The two countries have quarrelled over migrants crossing into Greece; then earlier this month Greece was appalled when Turkey said the Hagia Sophia museum in Istanbul, for centuries an Orthodox Christian cathedral, would be turned into a mosque .

Greece has said the Turkish naval move violates its sovereign rights. Prime Minister Kyriakos Mitsotakis spoke to German Chancellor Angela Merkel and said he would talk to other Greek political leaders about the escalation on Thursday.

Why the flare-up?

Nato allies Turkey and Greece are on separate sides in a race to develop energy resources in the Eastern Mediterranean.

In recent years, huge gas reserves have been found in the waters off Cyprus, prompting the Cypriot government, Greece, Israel and Egypt to work together to make the most of the resources. As part of that agreement, energy supplies would go to Europe via a 2,000km (1,200-mile) pipeline in the Med.

Last year Turkey stepped up drilling to the west of Cyprus, which has been divided since 1974, with Turkish-controlled northern Cyprus only recognised as a republic by Ankara. The division of the island was marked in Turkey this week, and Ankara has always argued that the island's natural resources should be shared.

Full report at BBC News