Oil companies aren't prepared to deal with a spill in the U.S. water of the Arctic Ocean, a new report warns.

Sub-zero temperatures, hurricane-force winds, low visibility, 10- to 30-foot seas and prolonged winter darkness would impede any cleanup attempts, says the report by the Pew Environment Group.

"The Gulf of Mexico catastrophe showed us the consequences of lax oversight and inadequate response capacity, even in temperate waters near population centers," said Marilyn Heiman, director of Pew's U.S. Arctic Program in a statement Wednesday.

"Sites proposed for drilling in Alaska's Arctic Ocean are some of the most remote areas on Earth and the challenges of drilling are formidable. Until reforms ensure that oil companies can respond to significant spills in real-world conditions, all proposed oil and gas leasing, exploration and development in the U.S. Arctic should be delayed."

Even the task of getting equipment and trained personnel to an Arctic spill site poses a challenge. Obstacles cited in the report include: A single road connects Prudhoe Bay, on Alaska's Beaufort Sea, to central Alaska, 415 miles south; no roads link the Chukchi Sea coast to the rest of Alaska; the nearest U.S. Coast Guard Air Station is 950 air miles away in Kodiak, Alaska, and no Coast Guard vessels are stationed in the Beaufort and Chukchi seas.

The report, "Oil Spill Prevention and Response in the U.S. Arctic Ocean: Unexamined Risks, Unacceptable Consequences," calls on the U.S. Department of Interior to block leasing and development until several reforms are undertaken.

Shell in 2008 spent $2.1 billion on the Arctic leases in the Beaufort and Chukchi seas and has embarked on an advertising and lobbying campaign in hopes of getting final approval for its long-delayed plans for exploratory drilling.

The U.S. Minerals Management Service estimates that the two Arctic seas hold up to 19 billion barrels of oil and up to 74 trillion cubic feet of natural gas.

Shell said last month it was willing to spend "tens and tens of millions of dollars" building an oil spill containment system for Arctic conditions if the U.S. government permits the drilling, the Financial Times reported. The company has maintained that the wells it proposes to drill in Alaska are in 150 feet of water, compared with 5,000 feet in the Gulf of Mexico.

U.S. Sen. Mark Begich, D-Alaska, who supports the drilling, said in a statement Wednesday that he would "continue to push the Obama administration for responsible Arctic development now to help meet America's energy, national and economic security."