"If we find they're not doing what they're supposed to be doing, we'll push them out of the way appropriately."

Salazar also said he believes BP is doing what it can to stop the leak, but that it may not be enough.

"I have no question that BP is throwing everything at the problem to try to resolve it because this is an existential crisis for one of the world's largest companies," he said.

"Do I have confidence that they know exactly what they're doing? No not completely."

Relying on BP

The US has acknowledged that only the company and the oil industry have the know-how to halt the deepwater spill.

Admiral Thad Allen, the chief of the Coast Guard, said on Sunday that the government is forced to rely on BP and the private oil sector to try to plug the gusher.

in depth

The oil spill began on April 20 when BP's Deepwater Horizon drilling rig exploded off the Louisiana coast, killing at least 11 workers and rupturing an underwater pipe.

BP announced on Sunday that its latest effort to contain the spill is not working as well as it should.

The company has deployed a long suction tube down to the larger of two leaks from the well, but a BP spokesman said it is capturing much less of the leaking oil than it was three days ago.

BP engineers are now preparing a "top kill," which involves pumping heavy drilling fluids into the ruptured well to try to shut it off.

'Breakdown of responsibility'

Barack Obama, the US president has blamed the spill on "a breakdown of responsibility" at BP and he has unveiled a commission to investigate the disaster.

Beachgoers in Louisiana are staying out
of the oil-polluted water [Reuters]

The administration is keeping the pressure on BP on many fronts as it strives to show it is being resolute in the face of what many believe is already the worst US oil spill, eclipsing the 1989 Exxon Valdez accident in Alaska.

Daren Beaudo, a spokesman for the company, told Al Jazeera on Sunday that BP has every intention of fully cooperating with the government and any investigation it conducts into the spill.

"We've been, from the beginning, cooperating completely with the government," he said.

"We pledged our commitment to all of the federal investigations ... to comply because we're as interested as anyone in understanding why this happened. 

"This shouldn't have happened. We don't know why this happened. To the point today we are working just as hard as we can to clean up the oil that's out there."