Turkey warned Greek Cypriots on Friday not to make a grab for energy reserves around the divided island and the president Tayyip Erdogan told oil companies to be careful they did not lose a "friend" by joining in.
Talks to reunite the ethnic Greek and Turkish sides of Cyprus collapsed in anger and recrimination in the early hours of Friday, ending a process many considered the most promising in generations to heal decades of conflict.
The Turkish prime minister Binali Yildirim, speaking at an energy conference in Istanbul, called on Greek Cypriots to refrain from taking "one-sided measures" after talks failed.
It was a clear reference to plans by the internationally recognised Greek Cypriot government to exploit potential hydrocarbon deposits around the Mediterranean island.
The government has already issued a maritime advisory for a natural gas drill from July to October.
"We want to remind once again that the hydrocarbon resources around Cyprus belongs to both sides," Mr Yildirim said.
"The Greek Cypriot leadership must seek a constructive approach rather than setting an obstacle for peace. We advise that they refrain from unilateral measures in the east Mediterranean."
Mr Erdogan, speaking later at the same conference, went further, with a not-very-veiled threat to oil companies who may be tempted to participate in the Greek Cypriots' plans.
"It is impossible to appreciate that some energy companies are acting with, and becoming part of some irresponsible measures taken by, Greek Cypriots," Mr Erdogan said. "I want to remind them that they could lose a friend like Turkey."
Greek Cypriots say it is its sovereign right to explore for hydrocarbons, and it has signed maritime delimitation agreements with most of its neighbours.
