New York's benchmark contract, light sweet crude for delivery in June, spiked at 40.15 dollars before ending at 40.06 dollars a barrel, up 1.13 dollars at a 13-and-a-half-year closing high.

Brent North Sea crude for June delivery soared 1.39 dollars to 37.36 dollars a barrel.

Saudi Arabia's oil minister Ali al-Naimi on Monday called for an increase in Opec’s production quota of not less than 1.5 million barrels per day -- comments which initially forced prices down.

But Fimat USA market analyst Mike Fitzpatrick said the Saudi promise was considered to be empty because Organization of Petroleum Exporting Countries (Opec) members already exceeded their quota by that amount.