which President Tayyip Erdogan said was part of even bigger reserves and could come onstream as soon as 2023.If the gas can be commercially extracted, the discovery could help Ankara cut its current dependence on imports - from countries such as Russia, Iran and Azerbaijan - for most of its energy needs.

“Turkey has realised the biggest natural gas find of its history in the Black Sea,” Erdogan said, adding that ultimately Turkey aims to become a net energy exporter.

The Fatih drill ship began work late last month in the Tuna-1 zone, about 100 nautical miles north of the Turkish coast in the western Black Sea.

“This reserve is actually part of a much bigger source. God willing, much more will come. As a country that depended on the outside for gas for years, we look to the future with more security now,” Erdogan said. “There will be no stopping until we become a net exporter in energy.”

Any reduction in Turkey’s energy import bill, which stood at $41 billion last year, would boost government finances and help ease a chronic current account deficit which has helped drive the lira to record lows against the dollar.

“I can say safely that with the economic and exploratory potential, we will remove the current account deficit from the agenda of our country,” said Finance Minister Berat Albayrak, speaking from the deck of the Fatih.

The lira TRYTOM=3 has strengthened since Erdogan first told energy executives on Wednesday that he had “good news” to announce. It slid however as he detailed the find and was down 0.4% at 1330 GMT.

Officials and analysts had cautioned that it could take up to a decade for gas from the Black Sea find to come online, and would need billions of dollars of investment to build up the infrastructure for production and supply.

The gas find is located in waters 2,100 metres deep, Energy Minister Fatih Donmez said, with drilling extending another 1,400 metres below the sea bed. “Our operations here are not finished. We will go down a further 1,000 metres ... and data shows it is probable we will reach gas there too.”

Turkey has been exploring for hydrocarbons in the Black Sea and in the Mediterranean - where its survey operations in disputed waters have drawn protests from Greece and Cyprus.

Erdogan said Turkey would accelerate operations in the Mediterranean.