BP pipeline leaks near Alaska's Prudhoe Bay

NEW YORK (Reuters) - BP Plc discovered an oil and gas spill on a pipeline that serves the giant Prudhoe Bay oil fields in Alaska over the weekend, a company spokesman said on Monday.

BP was assessing damages after it found the leak early Sunday, spokesman Steve Rinehart said. The line is one of dozens serving Prudhoe Bay, the biggest U.S. oil field complex, whose output usually tops 400,000 barrels per day.

Prudhoe output wasn't immediately affected, although BP may shut in some production as it repairs the line or idles others that share a T-shaped pipe support infrastructure, Rinehart said.

"There may be some associated impact with neighboring lines, but at this point there's no way to quantify that," Rinehart said.

Trans-Alaska Pipeline System (TAPS), the major conduit for Alaskan crude, was unaffected and shipped nearly 700,000 barrels a day Sunday, a spokeswoman said.

BP's spill occurred on an 18-inch common line carrying a mixture of crude, water and natural gas, Alaska's Department of Environmental Conservation said. The amount of crude spilled and the cause of the leak are under investigation.

The line wasn't operating when the leak was found, although it still held oil and gas, Rinehart said. The oil spill covered 8,400 square feet of "snow-covered tundra," according to a situation report. The spill area wasn't expanding, Rinehart said.

In 2006, BP faced serious operational issues in Alaska, when it discovered extensive pipeline corrosion following an oil spill. That forced the British oil giant to temporarily shut in much of Prudhoe Bay's output and later pay environmental fines.

Analysts said BP's newest pipeline fixes may result in some reduction of Alaskan crude output, but that might not affect oil prices much since U.S. crude stocks are high amid poor demand from refiners.

"Conditions are vastly different from (2006) when the previous BP incident in Alaska occurred," said Mike Fitzpatrick of MF Global in New York. "At that time every marginal barrel removed from the market had a supportive effect (on prices)."

The line affected by Sunday's spill is linked to the Lisburne production center, which processes some of Prudhoe Bay's output, according to a company website. A cleanup plan for the spill site is subject to approval by Alaskan authorities, Rinehart said.

BP shares fell on Monday by 1.6 percent on the London Stock Exchange.

(Additional reporting by Bruce Nichols in Houston and Robert Gibbons in New York; editing by Jim Marshall)