The Prudhoe oilfield produces 400,000 barrels of oil a day

BP said it shut down some production at the Prudhoe field after finding water leaking from a pipe used in a facility that separates water from crude oil.

However, the news had little effect on oil prices which fell on Tuesday.

In the US, light sweet crude slipped $1.30 to close at $64.97, while in London Brent crude closed 97 cents lower at $69.52.

Analysts said traders had shrugged off the leak as minor, and were instead taking profits on recent share gains.

Production cut

The Prudhoe facility produces around 400,000 barrels of oil a day.

"We expect the facility to be down a few days while repairs are made," said BP spokesman Ronnie Chappell. The group expects production to fall by just 25,000 barrels a day.

News of the leak comes as a US criminal investigation takes place into a incident at the facility last year which led to 200,000 gallons of oil leaking from the site.

At a hearing last week, BP America chief Bob Malone admitted there had been "extreme budget pressures at Prudhoe Bay", which had affected maintenance work.

BP has also launched an independent review of corrosion inspection and monitoring of all its pipelines at Prudhoe and across Alaska.