The world's largest oil producers intervened on Wednesday to try to cool oil prices, as Opec reassured customers it could raise output and Saudi Arabia, its biggest member, turned on the taps at two new fields ahead of schedule.

However, the effort did little to reverse the recent sharp rise in oil prices, which set new records in both the US and European key benchmark crude futures on Wednesday. Prices declined only slightly following the announcements from Opec and Saudi Arabia, suggesting that the oil cartel's ability to influence oil markets has been undermined.