Opec, however, has long argued that high oil prices have been driven by a weak US dollar and speculators on exchanges in the US and Europe, not by a shortage of supply.

Opec insists that it does not set prices, but regulates supply to meet demand. Abdullah al Badri, the Opec secretary general, said the move was misguided.

“It’s their policy and I’m not going to challenge it,” he said. “But I think this is not the way to handle any problem – problems should be solved with dialogue. You cannot go and just blame Opec or try to abolish Opec.”

Also yesterday, an industry consultant told Reuters that he estimated Opec would increase production by 700,000 barrels per day in May on the back of increases by Nigeria and Saudi Arabia.

The 13 members of Opec were expected to pump 32.4 million barrels per day this month, compared to 31.7 million in April, said Conrad Gerber of Petrologistics.