Italy's Eni and France's Total have discovered a promising natural gas field off Cyprus, Eni said on Thursday, saying the find looked geologically similar to the mammoth Zohr field off Egypt.
Further analysis was required to determine the range of gas volumes and define further exploration and appraisal operations, Eni said.
"Calypso 1 is a promising gas discovery and confirms the extension of the 'Zohr like' play in the Cyprus Exclusive Economic Zone (EEZ)," Eni said in a statement.
Eni is the operator of the offshore block with a 50 percent participation interest, while Total is a partner with the remaining 50 percent.
The Italian oil and gas group reported the Zohr discovery in 2015. Located in the Egyptian offshore Shorouk block about 190 km north of Port Said, Zohr holds an estimated 30 trillion cubic feet of gas, the largest ever discovered in the Mediterranean
Calypso in Cyprus's waters is an estimated 80 km away.
In Nicosia, Cypriot Energy Minister Yiorgos Lakkotrypis said an "extensive column" of clean natural gas was discovered.
"This is a particularly positive development because it is the second substantive discovery in the Cypriot EEZ (exclusive economic zone), which increases the reserves of Cyprus in natural gas," Lakkotrypis said, referring to an earlier discovery of about 5 tcf in 2011.
Perched on the maritime edge of two massive gas finds in the Levant Basin - Leviathan off Israel and Zohr off Egypt, Cyprus, which still relies on heavy and expensive fuel oil for its power stations, has been keen to emulate its neighbours' success.
But it also lies in a region of overlapping rivalries and geopolitical risk.
Cyprus is ethnically divided, and Turkey, which supports a breakaway Turkish Cypriot state in north Cyprus, says Greek Cypriots have no jurisdiction to explore for natural gas. Greek Cypriots say it is their sovereign right.
Greek Cypriots run Cyprus's internationally recognised government and has agreements in place on its EEZ with Egypt, Israel and Lebanon.
Turkey maintains that some of those boundaries fall onto its continental shelf. Parts of block 6, where Calypso is located on its fringe, is one of them, Ankara says.
Although Cyprus and Turkey have been verbally jousting for years, the disagreement triggered an unusual rebuke from Egypt on Wednesday. Any attempt by Turkey to diminish Egyptian economic interests - by contesting its 2003 EEZ accord with Cyprus - was "rejected and would be confronted", its foreign ministry spokesman said in a statement.
Reporting by Michele Kambas