NEW ORLEANS — Oil spewed uncontrolled into the Gulf of Mexico again Wednesday after an undersea robot bumped the cap being used to contain it, forcing BP engineers to remove the device and then scramble to reattach it.

The latest setback left nothing to stem the flow of oil at its source. A camera recording the well showed huge clouds of black fluid coming out of the seafloor. BP hoped to quickly replace the cap, which since June 4 had been carrying some of the oil gushing from the blown-out well to a surface ship.

In recent days, it was sucking up about 110,000 litres an hour, crude that spewed back into the Gulf on Wednesday. Another ship was still collecting a smaller amount of oil and burning it on the surface.

BP engineers removed the cap after the mishap because fluid seemed to be leaking, creating a possible safety hazard because of the flames above, and they were concerned ice-like crystals might clog it. They were working to replace it Wednesday night.

The latest problem with the nine-week effort to stop the gusher came as thick pools of oil washed up on Pensacola Beach in Florida and the Obama administration sought to resurrect a six-month moratorium on deepwater drilling.

Under the worst-case scenario, as much as 393,670 litres an hour -- 9.46 million litres a day -- is flowing from the site where the offshore rig Deepwater Horizon exploded April 20, killing 11 workers.

Bob Dudley, the BP managing director who took over the spill response from his company's embattled CEO Wednesday, said engineers expected to replace the cap in less than a day.

"It's a disruption, and the crew again did exactly the right thing because they were concerned about safety," he said. "It's a setback, and now we will go back into operation and show how this technology can work."

When the robot bumped into the equipment just before 10 a.m., gas rose through a vent that carries warm water down to prevent icy crystals from forming in the machinery, Coast Guard Adm. Thad Allen said.

Crews were checking to see if the crystals called hydrates had formed before attempting to put the cap back on.

Ed Overton, a professor emeritus of environmental science at Louisiana State University, said he suspects crews are pumping air into the line to flush out any water before they try to reattach the cap.

"It sounds pretty easy and straightforward, but nothing is easy and straightforward when you're doing it remotely from a mile away," he said.

In May, a similar problem doomed the effort to put a bigger containment device over the blown-out well. BP had to abandon the four-story box after the crystals clogged it, threatening to make it float away.

The smaller cap had worked until now. To get it to the seafloor, though, crews had to slice away a section of the leaking pipe, meaning the flow of oil could be stronger now than before.

Meanwhile, pools of oil washed up along kilometres of national park and Pensacola Beach shoreline and health advisories against swimming and fishing in the once-pristine waters were extended for 53 kilometres east from the Alabama border.

"It's pretty ugly, there's no question about it," Gov. Charlie Crist said.

The oil had a chemical stench as it baked in the afternoon heat. The beach looked as if it had been paved with a 6-foot(2-meter)-wide ribbon of asphalt, much different from the tar balls that washed up two weeks earlier.

"This used to be a place where you could come and forget about all your cares in the world," said Nancy Berry, who fought back tears as she watched her two grandsons play in the sand far from the shore.

The Obama administration was plotting its next steps Wednesday after U.S. District Judge Martin Feldman in New Orleans overturned a moratorium on new drilling, saying the government simply assumed that because one rig exploded, the others pose an imminent danger, too.

The White House promised an immediate appeal of his ruling. The Interior Department imposed the moratorium last month after the BP disaster, halting approval of any new permits for deepwater projects and suspending drilling on 33 exploratory wells.

Interior Secretary Ken Salazar said in a statement that within the next few days he would issue a new order imposing a moratorium that eliminates any doubt it is needed and appropriate.

"It's important that we don't move forward with new drilling until we know it can be done in a safe way," he told a Senate subcommittee Wednesday.

Attorneys for the oilfield services companies that sued over the moratorium filed court papers accusing the Obama administration of ignoring Feldman's decision. They said Salazar's comments about a new moratorium have had a chilling effect on the resumption of drilling.

Several companies, including Shell and Marathon Oil, said they would await the outcome of any appeals before they start drilling again.

BP's Dudley said that Americans have been too quick to blame his company for the environmental disaster, now in its third month.

"I'm somewhat concerned there is a bit of a rush to justice going on around the investigation and facts," he said.