Cypriot Director of Energy Solon Kassinis told the semi-official Cyprus News Agency Monday the U.S. firm Noble Energy had started exploratory drilling in a disputed "exclusive economic zone" south of Cyprus, close to Israeli waters in the Mediterranean Sea.
That brought quick response from Turkish Prime Minister Recep Tayyip Erdogan, who said in a televised statement Monday that his country would send "frigates, gunboats and its air force" to "constantly monitor developments in the area," The New York Times reported.
Erdogan later said his country would institute its own seismic explorations in the area, which contain major natural gas deposits claimed largely by Israel, the newspaper said.
Cyprus has been disputed between Turkey and Greece since the 1960s. A Turkish enclave in the island's north -- recognized only by Ankara -- was established after a 1974 Turkish invasion in response to a Greek-inspired coup.
The exclusive economic zone extending into the Mediterranean from Cyprus' south also is a matter of debate.
"We have different attitudes for the region that they have declared as an exclusive economic region," Erdogan said. "This is a disputed exclusive economic region and we have earlier conveyed to them that taking such a step in this disputed region would be incorrect."
Cyprus unveiled the drilling plans last month and Turkey quickly objected. Ankara has promised to sign a pact with the northern enclave to establish maritime boundaries and has hired a Norwegian vessel to conduct a survey in waters claimed by Greece, the Turkish daily Hurriyet reported.
Turkish Energy Minister Taner Yildiz said the surveys would "obviously" be carried out with a Turkish navy escort, adding, "there will be no stepping back from that."
A continental shelf delineation agreement between Ankara and northern Cyprus leading to exploration work is already drawn up and ready to go, Yildiz said, adding the Turkish Petroleum Corp. would be working with the unnamed Norwegian firm on the project.
The drilling dispute brought calls for restraint from the European Union, the United States and the United Nations.
"The European Union calls on all parties to make all efforts to reach a comprehensive settlement as soon as possible," Maja Kocijancic, a spokeswoman for EU foreign policy chief Catherine Ashton, said Monday in Brussels.
The episode, she said, reinforced the urgency of resolving the 37-year-old division of the country as Cyprus approaches its turn at the EU presidency next July.
But, she added, it won't produce a change in the scheduling, despite a warning Sunday from Turkish Deputy Prime Minister Besir Atalay that a Cypriot EU presidency would provoke a "real crisis" between his country and Europe.
"We will at that point freeze our relations with the EU," Atalay told Turkish-Cypriot Bayrak television.
U.S. Secretary of State Hillary Clinton said Washington supports the right of the Greek Cypriots to scout in the Mediterranean for energy.
Clinton told Turkish Foreign Minister Ahmet Davutoglu in New York Monday the best way to settle such economic development disputes in Cyprus is to end its division, the Voice of America reported.
Reconciliation talks between the Turkish north and the Greek south began in 2008 but haven't produced a settlement.