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. The find follows other significant gas discoveries in the Mediterranean in recent years. They are expected to have a major impact on the region’s economy and potentially offer Europe new supply options, allowing it to reduce its dependence on Russian gas imports. It also represents a major boost for Egypt, where power cuts caused by gas and oil shortages have often fuelled unrest.

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.

Eni, which is 30% state-owned, is the biggest foreign oil and gas producer in Africa, where it has significant operations in Libya. In 2011, it made huge finds off Mozambique, with an estimated 85tn cubic feet of gas in place.

It has operated for more than 60 years in Egypt and is one of the main energy producers in the country, with a daily output of 200,000 barrels of oil equivalent. In June, it signed an energy exploration deal with Cairo worth $2bn (£1.3bn), 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.

Egypt, which once exported gas to Israel and elsewhere, has become a net energy importer over the past few years. Under Sisi, Egypt’s state-owned gas company Egas has increasingly rationed supplies to much of the country’s industry, which has at times crippled production and hampered economic recovery.

The government has attempted to improve the energy situation by slashing state subsidies, paying down its debt to foreign energy firms and negotiating import agreements.