ANCHORAGE, Alaska (Reuters) - Oil major Shell said on Wednesday it has formally withdrawn a three-year plan for exploration in Alaska’s Beaufort Sea after it was stymied by concerns over the potential impact to whales, polar bears and other marine wildlife.

Customers fuel up at a Shell gas station in Westminster, Colorado in this file photo fromOctober 30, 2008. REUTERS/Rick Wilking

Shell said it informed the U.S. Minerals Management Service that it is shelving its 2007-2009 Beaufort plan and will soon file new exploration plans for 2010 that will be much smaller in scale to address litigation launched by environmentalists and North Slope residents.

“Over the last three years, Shell’s Beaufort Sea drilling objectives have become more focused with the acquisition and analysis of additional seismic data,” Pete Slaiby, Shell Alaska’s general manager, said in a statement. “As a result, the 2007-2009 plan no longer represents Shell’s current drilling approach.”

Shell had originally planned to drill nearly a dozen wells over three years at Sivulliq, a prospect in the Beaufort Sea where oil had been discovered, along with other wells at another Beaufort Sea prospect. The drilling was to have started in 2007 and been completed this year, according to Shell’s original plans.

But after a court ruled in November that federal officials failed to address environmental impacts when they granted the company a permit, Shell said it will not pursue the drill program in 2009.

Lawsuits challenging the drilling resulted in the 9th Circuit Court of Appeals order overturning the MMS decision granting permission for that program. The lawsuits, filed by environmentalists, Native groups and the North Slope Borough, said the MMS authorized the drilling without adequately reviewing impacts to wildlife in the sensitive region.

Shell’s 2010 exploration plan will be much reduced from the earlier proposed program, company officials said. It will span one year instead of three, use a single drilling rig instead of two and seek to drill two wells in a single year instead of four, officials said.

Like the previous plan, the 2010 plan will focus on Sivulliq, said company spokesman Curtis Smith.

Shell could have waited for the 9th Circuit Court to reverse its ruling from six months ago and allow exploration to proceed under the old plan, Smith said. The San Francisco-based court in March vacated its November ruling but did not indicate what decision would follow.

“It could have gone either way,” Smith said. The company decided, ultimately, that scaling back its Beaufort exploration plans was a better strategy, he said.

A spokeswoman for one of the environmental litigants said Shell’s move was good news.

“We’re certainly happy to hear that they’ve withdrawn their plan for exploration,” said Betsy Beardsley of the Alaska Wilderness League. “It’s no surprise. If they want to have an exploration plan, the one they have right now isn’t good enough.”

Shell spent $84 million in 2005 and 2007 acquiring Beaufort Sea leases.

The Sivulliq prospect, within the territory acquired by Shell, is known to hold technically recoverable oil. The site was formerly known as Hammerhead, and drilling in the 1980s by Shell and others resulted in the discovery. But Hammerhead was abandoned for economic reasons.

Shell officials have also said they hope to start exploration drilling in Alaska’s Chukchi Sea next year. However, those plans are clouded by an April 17 ruling from the U.S. Court of Appeals for the District of Columbia, which tossed out the five-year leasing program under which Shell and other companies acquired their Chukchi Sea exploration rights.

Shell last year spent $2.1 billion on high bids for Chukchi leases, part of a record-setting $2.66 billion lease sale.

The MMS estimates the outer continental shelf of the Beaufort holds 8.22 billion barrels of technically recoverable oil and 27.64 trillion cubic feet of recoverable natural gas. The MMS estimates that the Chukchi’s outer continental shelf holds 15.38 billion barrels of recoverable oil and 76.77 trillion cubic feet of recoverable natural gas.