LONDON –  Production at a BP PLC (BP.LN)-run oil and gas field in the North Sea has been halted after a leak was discovered in an underwater connecting pipeline, the U.K. energy giant said Monday.

"BP can confirm that a small oil leak--caused by a hairline fracture to a fitting on an infield flowline on the Foinaven Field--was identified at approximately 01:30 Sunday. Production from the field was immediately shut down and the leak was stopped. This was confirmed by a remotely operated vehicle inspection 50 minutes later at 02:20," the company said.

The pipeline may have leaked for up to twelve days before it was discovered, a BP spokesman said.

However, BP said no oil was visible on the sea surface and that there was no evidence of ongoing pollution. The spokesman wasn't able to quantify how much oil might have leaked into the sea but cautioned that the volumes passing through the pipe were expected to be "low...around 88% water, 12% crude."

Production at the field, which had averaged around 43,000 barrels of oil a day, remains shut down, BP said. The spokesman said it was too early to determine when production would likely resume--an investigation into the cause of the incident still has to take place -- but that it would be a matter of weeks rather than months.

The Department of Energy and Climate Change said it was aware of the incident.

"BP have confirmed...that actions have been taken to halt any further release [of hydrocarbons]. DECC has received confirmation that the leak has been stopped and further aerial surveillance has found no evidence of oil at sea."

The department said it has initiated its incident response procedures and made contact with all relevant agencies, including the U.K. marine and coastal services.

Foinaven, located 190 kilometers west of the Shetland Islands, was the U.K.'s first deepwater field and was brought on line in mid 2000. BP operates the field with a 70% interest, while U.S. firm Marathon Oil Corp. (MRO) holds a minority stake.

Oil produced from Foinaven is mostly sold to refineries in North-West Europe. However, North Sea crude traders said crude prices in the region have been unaffected by the shutdown so far as the field's production volumes are small.

"It's a small field, only one to two cargoes a month," one trader said, while others said it would only have a price impact if it were to stay shut for a long time.

The incident is the second offshore pipeline leak to affect a major North Sea producer in six months. In August, Royal Dutch Shell PLC (RDSA.LN) battled for a week to stem a ruptured underwater pipe at its Gannet Alpha platform in the U.K. North Sea. Some 1,300 barrels of oil spilled into the sea before divers managed to seal the pipe, although none of the oil reached land.

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