They were forced to conclude that a half-dozen of them had dropped in volume and were leaking anywhere from a few gallons to a few hundred gallons of radioactive material a year.

FORBES: Nuclear Waste Leaks Worse than Thought in Washington

Before the explosion, the rig carried 2.6m litres of diesel fuel and was pumping 8, 000 barrels (1.27m litres) of crude oil a day - a volume which may still be leaking from the well into the Gulf of Mexico.

BBC: Tackling oil rig disaster 'number one priority' - Obama