Iran has discovered a new oil field in the country’s south with an estimated 50 billion barrels of crude oil, its president said.

The find could boost the country’s proven reserves by a third as it struggles to sell energy abroad amid US sanctions.

The announcement by Hassan Rouhani comes as Iran faces crushing US sanctions after the country pulled out of its nuclear deal with world powers last year.

Mr Rouhani made the announcement in a speech in the desert city of Yazd.

He said the field was located in Iran’s southern Khuzestan province, home to its crucial oil industry.

Attack on major oil facilities in Saudi Arabia: In pictures Show all 10 1 /10 Attack on major oil facilities in Saudi Arabia: In pictures Attack on major oil facilities in Saudi Arabia: In pictures Smoke billows from multiple fires at the Aramco oil processing facility in Abqaiq, Saudi Arabia on 14 September Reuters Attack on major oil facilities in Saudi Arabia: In pictures Thick black smoke billows from a fire following drone strikes on major oil facilities in Abqaiq, Saudi Arabia Planet Labs Inc/Reuters Attack on major oil facilities in Saudi Arabia: In pictures The Aramco oil processing facility in Abqaiq, Saudi Arabia prior to the drone strikes on 14 September AP Attack on major oil facilities in Saudi Arabia: In pictures Damage is seen to the Aramco oil processing facility in Abqaiq, Saudi Arabia following drone strikes on 14 September, the previous day (Image 1 of 2) AP Attack on major oil facilities in Saudi Arabia: In pictures Damage is seen to the Aramco oil field in Abqaiq, Saudi Arabia following drone strikes on 14 September, the previous day (Image 2 of 2) AP Attack on major oil facilities in Saudi Arabia: In pictures Damage is seen to the Aramco oil field in Khurais, Saudi Arabia following drone strikes on 14 September, the previous day (Image 1 of 2) AP Attack on major oil facilities in Saudi Arabia: In pictures Damage is seen to the Aramco oil field in Khurais, Saudi Arabia following drone strikes on 14 September, the previous day (Image 2 of 2) AP Attack on major oil facilities in Saudi Arabia: In pictures Smoke billows from multiple fires following drone strikes on major oil facilities in Abqaiq, Saudi Arabia AFP/Getty Attack on major oil facilities in Saudi Arabia: In pictures Smoke rises from a fire following a drone strike at the Aramco facility in Abqaiq, Saudi Arabia on 14 September Reuters Attack on major oil facilities in Saudi Arabia: In pictures Smoke is seen following a fire at the Aramco oil processing facility in Abqaiq, Saudi Arabia on 14 September Reuters

He added that 50 billion barrels would be added to Iran’s proven reserves of some 150 billion.

Proven reserves are those that are commercially feasible to extract.

The new oil field could become Iran’s second-largest field after one containing 65 billion barrels in Ahvaz.

“I am telling the White House that in the days when you sanctioned the sale of Iranian oil, the country’s workers and engineers were able to discover 53 billion barrels of oil,” Mr Rouhani said.

Iran currently has the world’s fourth-largest proven deposits of crude oil and the world’s second-largest deposits of natural gas.

It shares a massive offshore field in the Persian Gulf with Qatar.

Since the US withdrew from the 2015 nuclear deal, the other countries involved – Britain, Germany, France, Russia and China – have been struggling to save it.

However, they have offered no means by which Iran can sell its oil abroad.

The collapse of the nuclear deal coincided with a tense summer of mysterious attacks on oil tankers and Saudi oil facilities that the US blamed on Iran.