BP last night faced a two-pronged attack from shareholders and legislators following the partial shutdown of the Prudhoe Bay oilfield in Alaska, the largest in the US.

A shareholders' group has filed a lawsuit against the British giant alleging it knew of severe corrosion of the pipeline for years but took no action.

And a powerful federal committee plans calling senior executives to account for " chronic neglect" of infrastructure.

The shareholders' suit alleges BP took no steps to monitor and repair corrosion in the Prudhoe Bay transit lines that ferry oil into the 800-mile trans-Alaska pipeline.

The closure has more than halved the field's daily 400,000-barrel output. Oil from Prudhoe Bay makes up eight per cent of US domestic supply.

BP chief executive Lord (John) Browne and more than a dozen top BP executives were named as defendants in the suit filed in New York District Court.

The suit, which seeks unspecified damages, was brought by investor Sue Pincus on behalf of BP shareholders "to remedy the severe harm caused to the company by its senior officers' and directors' mismanagement and neglect".

BP said it does not comment on pending litigation.

The spillage of an estimated 267,000 gallons of crude from the BP lines in March was the largest ever on the North Slope of the Alaskan oil field.

Further testing, and a smaller spill in July, prompted the shutdown.

BP estimates the costs along 16 miles of pipeline will reach about $170 million (£89.5 million).

It has not disclosed how costs will be shared by the field's other owners, ConocoPhillips and Exxon Mobil.

Meanwhile, the British oil giant is also facing federal scrutiny in the US.

A congressional committee has scheduled a hearing to examine BP's management practices on the field near the edge of the Arctic Ocean for September 7.

They also face questions about an explosion last year at a refinery in Texas that killed 15 workers and injured more than 170 others.

The hearing follows BP's assurances that the March spillage at Prudhoe Bay was a one-off and that its corrosion control system was adequate.

Senator Joe Barton, chairman of the House Energy and Commerce Committee in Washington DC, said in a letter to Lord Browne: "The fact that BP's consistent assurances were not well grounded is troubling and requires further examination.

"The consequent disruptions to energy production and delivery and resultant adverse impacts on American consumers and the American economy are not excusable, particularly in light of substantial evidence that BP's chronic neglect directly contributed to the shutdown.

"This latest incident calls in question BP's commitment to safety, reliability and responsible stewardship of America's energy resources.

BP said the company had not been approached about the September 7 hearing but was co-operating fully with state and federal officials.

Spokesman Tom Mueller said the company was spending $72 million (£38 million) on an anti-corrosion programme.

"Frankly, we thought it was adequate but clearly it was not," he said. "Now our job is to repair lines and investigate what corrosion activities are going on inside that line."