U.N.-led talks to reunify the Mediterranean island of Cyprus could be derailed by Turkey's obstruction of vessels searching for oil offshore, Cypriot President Demetris Christofias said in a letter made public on Wednesday.

U.N.-led talks to reunify the Mediterranean island of Cyprus could be derailed by Turkey's obstruction of vessels searching for oil offshore, Cypriot President Demetris Christofias said in a letter made public on Wednesday.

Cyprus has sent two protest letters to the U.N. complaining of "provocation" by Turkish naval vessels attempting to impede oil exploration off its southern coast. Nicosia says four "serious incidents" took place last month.

"I find myself in the unpleasant position of expressing my dismay over the continuation of such aggressive actions," said Christofias' complaint to U.N. chief Ban Ki-moon dated Nov. 25.

"The continuation of these incidents, I am sad to observe, unavoidably impacts negatively on our efforts to reach a negotiated solution to the Cyprus problem," he said.

Cyprus has been divided along ethnic lines since 1974 when Turkey occupied the northern third of the island in response to an Athens-engineered Greek Cypriot coup seeking to unite the country with Greece.

Christofias and Turkish Cypriot leader Mehmet Ali Talat in September launched fresh negotiations in a U.N.-brokered bid to reunify the island, but the initiative has made little tangible progress.

Complicating the issue is recent tension between the internationally recognized Greek Cypriot government and Turkey over oil exploration rights. Cyprus has signed gas and oil exploration deals with Egypt and Lebanon, sparking Turkish protests that the deals damage the rights of the island's breakaway Turkish Cypriot entity.

On Nov. 13, a Turkish warship turned back a Norwegian-flagged exploration vessel sailing off Cyprus' southern coast, after which Nicosia accused Ankara of having resorted to 19th century-style gunboat diplomacy.

There were similar incidents on Nov. 19, 21 and 24, according to the government.

"I am doing everything in my power to protect the process of negotiations and to bring it to a positive conclusion," said Christofias. "It is important, at the same time, that the U.N. and the international community support these efforts through effective solidarity."

Greece has backed Cyprus in its oil row with Turkey, having itself had a similar spat with Ankara also last month. On Nov. 15, a Norwegian survey ship commissioned by the Turkish government called off a search in the southeastern Aegean after Athens complained the exploration was held over an area of Greek seabed.

A 12th round of Cyprus peace talks are scheduled to resume Dec. 16 to continue negotiations on power sharing.