Turkish President Tayyip Erdogan makes a speech at the 22nd World Petroleum Congress in Istanbul, Turkey, July 10, 2017. REUTERS/Murad Sezer

ANKARA (Reuters) - Turkish President Tayyip Erdogan said on Monday an important opportunity was wasted at last week’s failed Cyprus talks, and warned it was unacceptable that energy companies were taking part in what he called irresponsible measures by Greek Cypriots.

“It is impossible to appreciate that some energy companies are acting with, and becoming part of some irresponsible measures taken by, Greek Cypriots. I want to remind them that they could lose a friend like Turkey,” Erdogan told a petroleum conference in Istanbul.

Erdogan did not name the companies. Last month, Cyprus issued a maritime advisory for a natural gas drill from July to October in a step opposed by Turkey, which challenges the divided island’s jurisdiction to search for hydrocarbons.

Erdogan also stressed that hydrocarbon sources in waters around Cyprus should belong to all sides on the island.

“What we expect from anyone who takes sides in the developments in Cyprus is that they should refrain from steps that might pave the way for new tensions in the region,” he said.

Total won an offshore exploration license from Cyprus for drilling this year.

When asked by Reuters at a petroleum conference in Istanbul whether drilling by the company could alienate Turkey, Arnaud Breuillac, president of exploration and production at Total said the company had “no concerns”.