BP has pledged to spend $550m on maintaining pipelines in Alaska

A serious spillage and the discovery of corroding pipes forced it to halt half it operations at its Prudhoe Bay site.

This meant BP produced 3.8 million barrels of oil per day between July and September - down from more than 4 million in the previous three months.

Output was also slightly lower than in the same period a year ago - when hurricanes had hit its operations.

String of problems

Last month, US Congress accused BP of "unacceptable" neglect of its pipelines in Alaska.

Under questioning, BP bosses admitted some failures but said Prudhoe could resume full production in October.

The silver lining is that BP remains an oil behemoth in global terms Richard Hunter, Hargreaves Lansdown See BP's share price

Shares in BP have slipped 20% since April - with the problems at Prudhoe Bay compounding a string of other woes, including investigations into its trading operations by US regulators and a fire at its Texas City plant which killed 15 workers last year.

Production at its Thunder Horse platform in the Gulf of Mexico is to be delayed due to safety worries. The site was damaged by a hurricane in 2004.

The plunging price of crude oil - which on Wednesday dipped to below $59 a barrel - is also set to hit profits.

"These are torrid times for BP", said Richard Hunter of Hargreaves Lansdown Stockbrokers, adding that the latest update on production did "little to allay the general malaise surrounding the company".