The leak was caused by an explosion on April 20 aboard the Deepwater Horizon rig which killed 11 oil workers.

The rig, leased by BP from owners Transocean, sank two days later, rupturing the well pipe in several places and allowing oil to gush into the Gulf of Mexico unchecked ever since.

in depth

Doug Suttles, BP's chief operating officer, said the company pulled the insertion tube back to the surface to readjust its connection to a tanker intended to collect oil at the surface.

BP was working again to insert it and expects to be pumping at least some of the oil to the surface by Saturday night.

Dispersant spray

BP has also began spraying chemical dispersants on Saturday beneath the sea, a contentious development because it has never been done underwater.

Federal regulators had a day earlier approved the underwater use of the chemicals, which act like a detergent to break the oil into small globules and allows it to disperse more quickly into the water or air before it comes ashore.

"We didn't cross this threshold lightly," Coast Guard Rear Admiral Mary Landry said of the dispersants.

"This is a tool that will be analysed and monitored," she said.

Ken Salazar, the interior secretary who first disclosed the insertion tube setback, said at that high-level government officials were convening over the weekend to discuss the best way to end the spill.

On Friday,Obama assailed oil drillers and his own administration as he ordered extra scrutiny of drilling permits.

Obama condemned the shifting of blame by oil executives and denounced a "cozy relationship" between the companies and the federal government.