ANCHORAGE, Alaska - Efforts to assess an oil spill in a pristine wildlife refuge in remote Alaska were stalled early Sunday due to extreme weather, as 10 surviving crew members of a broken Malaysian freighter came ashore for questioning.

Ten of the original 26 crew of the Malaysian-flagged Selendang Ayu arrived Saturday in Dutch Harbor, Alaska, where they were to meet with investigators from the National Transportation Safety Board (NTSB), the US Coast Guard said.

The NTSB is investigating the marine accident, which has sent an unknown amount of heavy fuel oil gushing into the Bering Sea, as well as the crash of a Coast Guard helicopter that lost six of the ship's crew shortly after rescuing them.

The 222-meter (738-foot) freighter, carrying a shipment of soy beans from the northwestern US state of Washington to China, ran aground Wednesday off Unalaska Island in the Aleutian island chain, after its engines failed the day before.

A Coast Guard Jayhawk helicopter was plucking the final sailor from the freighter late Wednesday when it crashed next to the ship, plunging the 10 people on board into frigid, pitch-black seas and triggering an intensive two-day search.

A second Coast Guard helicopter rescued the crew of the wrecked helicopter and one more man from the freighter.

But rescuers on Friday gave up the search for six other missing sailors, who had been wearing only street clothes when they plunged into the 43-degree-Fahrenheit (six degree Celsius) water.

Those lost include four Indians, one Chinese national and a Filipino, a Coast Guard officer told AFP.

Shortly after the crash, the Selendang Ayu -- carrying 483,000 gallons of heavy bunker fuel and 21,000 gallons of diesel fuel -- broke in two, raising fears of an environmental disaster in the same general area off Alaska where the oil tanker Exxon Valdez hit a reef and caused the world's worst oil spill almost 16 year ago.

An overflight of the wreckage Saturday showed oil leaking from both sections of the vessel, though it was unclear how many fuel tanks were involved, the Alaska Department of Environmental Conservation said in a situation report.

"Response is limited due to severe weather conditions," the report said. "Extreme weather conditions continue to dictate the cancellation of planned activities."

Gale conditions were predicted in the area overnight, with winds up to 45 knots, 7.3-meter (24-foot) seas, snow showers and freezing rain.

Coast Guard teams are waiting to skim oil off the water, salvage the wreckage, contain the spill and begin rescuing birds and other wildlife affected by the spill.

The visually spectacular area -- located in a chain of islands stretching thousands of kilometers (miles) into the Bering Sea -- is accessible only by water or air.

The land is part of the Alaska Maritime National Wildlife Refuge, nesting haven for 40 million seabirds and home to numerous marine mammals including the endangered Steller sea lion and western Alaska sea otter.

"This is a very serious spill," Kurt Fredriksson, acting commissioner of the Alaska Department of Environmental Conservation said Friday.

"It's going to be very difficult to deal with. It's difficult oil ... and a sensitive shoreline."

The contamination could be the largest and gravest in Alaska since the sinking of the Exxon Valdez in 1989, several hundred kilometers to the east.

On March 24, 1989, more than 40 million liters of oil sullied Prince William bay when the Valdez hit a reef, triggering the worst oil spill in US history.

The Selendang Ayu is operated by Singapore-based IMC Transworld.

Ayu Navigation of Port Klang, Malaysia is the "potential responsible party," according to the Alaska Department of Environmental Conservation situation report.