Royal Dutch Shell will repay a $2bn (€1.7bn) debt to the National Iranian Oil Company when sanctions on Iran are lifted and will consider investing in the country’s vast energy sector, Shell’s boss for new business said.

Under pressure to lower stubbornly high oil prices, Opec ministers were gathering in Austria today to try to lower crude costs and ease the brakes on the global economy.

OPEC warned today that oil prices, already hovering near US 50 a barrel, would remain high through the spring, even as the cartel decided to keep its production ceiling at 27 million barrels a day.

OPEC agreed today to raise its production ceiling by two million barrels-a-day next month in a bid to bring down uncomfortably high prices of crude oil.

OPEC countries looked set to postpone cutting back their oil production target - despite fears of a seasonal dip in demand for crude - as their representatives prepared to meet in Algiers today.