Under the terms of a five-year accord, Russia would help Iran organise oil sales as well as "cooperate in the oil-gas industry, construction of power plants, grids, supply of machinery, consumer goods and agriculture products", according to a statement by the Energy Ministry in Moscow.

However, the Russian government mysteriously withdrew that statement last night, saying it would issue a new one on Wednesday.

Despite the U-turn, news of a possible agreement hit US markets. The Dow fell 139 points, or 0.8pc, led by energy companies such as Chevron, down 2.5pc, and ExxonMobil, down 1.9pc. Brent Crude fell 1.5pc before recovering to trade down 0.7pc at $104.61.