ISTANBUL—The United States is deeply concerned by Turkey's announced intentions to begin offshore drilling operations in an area claimed by Cyprus as its exclusive economic zone, a State Department spokesperson said on May 5.

Turkish media on Saturday cited Foreign Minister Mevlut Cavusoglu as saying a Turkish ship had started drilling in areas for which northern Cypriot authorities had issued a permit, a move likely to stoke tensions with Cyprus and Greece.

Turkey and the internationally recognised Greek Cypriot government have overlapping claims of jurisdiction for offshore oil and gas research in the eastern Mediterranean, a region thought to be rich in natural gas.

"The United States is deeply concerned by Turkey's announced intentions to begin offshore drilling operations in an area claimed by the Republic of Cyprus as its Exclusive Economic Zone," said State Department spokesperson Morgan Ortagus.

"This step is highly provocative and risks raising tensions in the region. We urge Turkish authorities to halt these operations and encourage all parties to act with restraint," the statement said.

Any escalation between Turkey and the United States could put more pressure on relations already strained on several fronts, including missile defense and military operations in Syria.

Cavusoglu had said in February that Turkey would soon begin drilling for oil and gas near Cyprus and on Saturday state-owned Anadolu news agency reported him as saying during a trip to northern Cyprus that drilling had begun.

Turkey launched its first drillship "Fatih" in October to drill off the coast of Turkey's southern Antalya province. It said a second ship that it purchased would operate in the Black Sea, but was diverted to the Cyprus area.

Breakaway north Cyprus, which is supported by Turkey, says any offshore wealth also belongs to them, as partners in the establishment of the Republic of Cyprus in 1960.

The island was divided in 1974 after a Turkish invasion triggered by a brief Greek-inspired coup. Countless peacemaking endeavours have failed, and offshore wealth has increasingly complicated peace negotiations, with Greek Cypriots saying the matter is not up for discussion

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