Following remarks last week by Turkish Prime Minister Recep Tayyip Erdogan affirming Ankara's readiness to deploy its navy across the Mediterranean, Greek Cypriot leader Dimitris Christofias issued a statement denouncing Turkish "threats" and saying EU-member Greek Cyprus would expect a response from its foreign allies.
A spokesman for Turkey's foreign ministry hit back by criticising the plan by the Greek Cypriot administration to start exploiting oil and gas reserves before having reached a peace settlement with Turkish speakers whose administration in the north of the island is recognised only by Ankara.
The exchange of rhetoric over the undersea resources of the Levant Basin reflects long-standing territorial disputes over who controls the waters between Greek Cyprus, Turkey, Syria, Lebanon, Israel, the Palestinian Gaza Strip and Egypt.
It comes as efforts to narrow differences between Greek and Turkish Cypriots on ending the 37-year division of the island are stalled ahead of an October summit called by the United Nations, and as relations between Israel and Turkey have been soured by last year's Israeli raid on a Turkish ship off Gaza.
Christofias said in his statement that his government would press ahead with plans to explore for oil and gas: "Concerning the possibility of Turkey committing an unlawful act, something which we hope will not happen, we will expect a strong and effective response from the international community."
He added: "In addition to questioning the sovereign rights of the Cyprus Republic, Turkey is also threatening our country and its associates ... It is causing tension in the region, sending the message that it acts like a troublemaker and violates international norms."
Turkey says "not acceptable"
Texas-based Noble Energy, under licence from the internationally recognised administration of Greek Cyprus, is expected to start exploration work in one offshore sector southeast of the island around the beginning of October. Tenders for other offshore blocks are expected later this year or next.
In response to Christofias, a Turkish foreign ministry spokesman told Reuters: "The Greek Cypriots are creating a fait accompli in the eastern Mediterranean while they are negotiating with the Turkish Cypriots. This is not acceptable because the natural wealth of the island belongs to both sides."
Christofias said that Turkish Cypriots, who have largely depended on Ankara since Turkey intervened the island in 1974 after a Greek-inspired coup, would have their share of the resources once there was a political settlement.
The US Geological Survey last year estimated a mean of 1.7 billion barrels of recoverable oil and a mean of 122 trillion cubic feet of recoverable gas in the Levant Basin Province, although disputes over control have held back exploration.
Israel has recently reported two major gas finds.