Updated

A U.S. energy firm has begun exploratory drilling for oil and gas off the coast of Cyprus, the divided island's energy chief confirmed Monday, despite strong warnings from Turkey not to do so.

The dueling comments reflected an escalating dispute over mineral deposits in the eastern Mediterranean, complicated by the status of Cyprus. The island has been divided since 1974 into an internationally recognized Greek Cypriot south and a breakaway Turkish Cypriot north, which is recognized only by Turkey.

In a significant escalation of tensions, Turkey said Monday it would send warships to protect its claims to undersea resources off the coast of Cyprus if the U.S. firm began drilling.

Cypriot energy chief Solon Kassinis told The Associated Press that workers on a rig belonging to Houston-based firm Noble Energy have already drilled 260 feet (80 meters) beneath the seabed at a location 115 miles (185 kilometers) off the island's southern coast.

The area is near sizable gas finds within Israeli waters, and within Cyprus' exclusive economic zone -- an area marked out following agreements with Egypt, Israel and Lebanon delineating Mediterranean undersea borders to facilitate the search for mineral deposits.

The Turkish government does not recognize the Cypriot government in the south, and vigorously protested the August announcement of Noble's intentions. Turkey says the Greek Cypriot drilling can derail long-running talks to reunify the island.

Turkish Energy Minister Taner Yildiz said unless Cyprus halted the planned drilling, his country would send out its own energy research ship within a week, and the Turkish navy would "obviously" escort it.

"This work will be carried out together with the escort," Yildiz told reporters. "There will be no turning back on this issue."

Turkey has been pursuing an increasingly muscular foreign policy since the re-election of its religiously rooted government in June. It expelled the Israeli ambassador this month in a dispute over a deadly raid on a Turkish aid convoy trying to break the Israeli blockade on the Gaza Strip last year and pledged to send its navy to escort future aid convoys.

Cyprus' President Dimitris Christofias on Sunday accused Turkey and Turkish Cypriots of "clamoring needlessly," saying it would take another year until experts can determine the quality of the deposits and the feasibility of extracting them.

"If they truly want to jointly exploit this seaborne treasure that nature granted us, they have to seriously sit at the negotiating table," Christofias told Greek Cypriots in London. "If and when the Cyprus problem is solved, we will share this gift."

Christofias reiterated his country's position that any agreement between Turkey and the breakaway Turkish Cypriot state to search for offshore deposits would contravene international law.

"They can't talk about the rights of the illegal state," he said.

Yildiz, the Turkish energy minister, said: "Our wish is that we do not reach such a point, and that the work they are undertaking with Noble comes to an end before it even begins."

Turkey had discussed the issue with U.S. officials but not with the company itself, Yildiz said, adding that the risks for the company are considerable.

Turkey has also renewed threats to freeze all ties with the European Union if Cyprus is allowed to assume the presidency of the 27-nation group before a settlement that would allow the Turkish north to be a legitimate representative of the reunified state.

Turkey's deputy prime minister, Besir Atalay, told Turkish Cypriot Bayrak television this week that "a real crisis will erupt between the EU and Turkey" if the Greek Cypriot government takes over the EU's six-month rotating presidency in July 2012.

"We will at that point freeze our relations with the EU," Atalay said.