Washington, May 18 (DPA) US President Barack Obama was expected to call for a special probe of the BP oil well rupture in the Gulf of Mexico as US officials Monday dismissed growing worries about massive undersea oil plumes from the leak.

The ongoing oil spill took a possible political toll as the top federal official in charge of regulation of offshore oil drilling resigned.

Meanwhile, Homeland Security Secretary Janet Napolitano went before the US Senate to describe the strong and speedy government response to the looming ecological and economic disaster.

But senators were dissatisfied, demanding to know how they could expand offshore drilling when the oil industry is so ill prepared for such accidents.

The Washington Post, citing an unnamed administration official, reported late Monday that Obama would set up an independent commission to investigate the well disaster.

BP said Monday it would never attempt commercial extraction of oil from the well that ruptured after the April 20 drill rig explosion, which killed 11 people.

"There is no intent to ever, ever, produce this well," BP's chief operating officer Doug Suttles told reporters.

BP had its first ray of hope in four weeks as crews started siphoning about 1,000 barrels a day - out of the estimated 5,000 barrels now leaking daily - to a surface vessel. Company officials hope to boost that to 2,000 barrels a day.

But growing anger among Gulf coast residents and the broader US public over revelations that the federal government failed to properly license and inspect many of the offshore drilling and production operations overshadowed the small success.

Chris Oynes, associate director of the offshore energy and minerals management programme at the Interior Department's Minerals Management Service (MMS), resigned Monday, an agency spokesman told the Bloomberg financial news agency. It was not clear if his departure was connected to the growing scandal.

MMS officials testified to a Coast Guard inquiry last week in New Orleans that safety inspections that might have prevented the April 20 blow-up were left up to the oil companies themselves. MMS failed to insist on required environmental impact assessments before granting licenses for drilling, reports said.

There are plans to split safety regulatory functions from revenue-collecting duties at MMS.

Most of BP's response to the looming environmental disaster is focussed on keeping the slick from reaching shore and skimming or burning off as much as possible.

On Sunday, The New York Times reported that scientists on the research vessel Pelican were finding huge underwater oil plumes in the Gulf's deep waters, evidence of the threat to underwater ecology. The plumes could be carried by a loop current around the Florida peninsula and up the US Atlantic Coast, scientists warned.

On Monday, US officials cautioned that those findings were premature. Coast Guard Rear Admiral Mary Landry, who is overseeing response efforts, said the oil was "several miles from the loop current".

Charlie Henry of the National Oceanic and Atmospheric Administration said that the information from Pelican researchers had been "taken out of context and was incorrect".

"None of the quantitative analyses have been done," he told reporters.

Scientists are worried about the US approval of dispersants being applied at the source of the leak, saying such chemicals have never been used at an ocean depth of 1.6 km.

BP's Suttles defended the dispersants, which he says break down oil into smaller drops, making it easier for bacteria to break down the pollution.

"I know there's a lot of concern. These are tradeoffs," he said. "We don't want this oil to come ashore."

By week's end, BP hopes to plug up the leak with a "top kill", forcing fluids that are heavier than oil through a pipe that sticks out to the side of the damaged wellhead. That would be followed up by cement, Suttles said.

The only long-term solution is the relief well being drilled to intersect with the ruptured well's bore hole. Mud and cement will be fed through it, but it won't be finished until late July or August.