Eni said in a statement that the Zohr field, which covers an area of about 60 square miles (100sq km), could hold as much as 30tn cubic feet of gas.

“Zohr is the largest gas discovery ever made in Egypt and in the Mediterranean Sea and could become one of the world’s largest natural-gas finds,” it said, adding that it had full concession rights to the area.

Eni said the discovery was at a depth of 1,450 metres (4,757 ft), and that it planned to fast-track development of the site using existing infrastructure. It said yet more gas might be discovered in future drilling.

In June, it signed an energy exploration deal with Cairo worth $2 bn (£1.3 bn), allowing it to explore in Sinai, the Gulf of Suez, the Mediterranean and the Nile delta. In July, Egypt raised the price it pays Eni for the natural gas it produces.

“This historic discovery will be able to transform the energy scenario of Egypt,” said Eni’s chief executive, Claudio Descalzi, who met the Egyptian president, Abdel Fatah al-Sisi, on Saturday to discuss the find.