Crews aboard two aircraft which flew over an oil drilling ship that went aground in a severe Alaska storm say there is no sign that the vessel is leaking fuel or that its hull has been breached.
The Royal Dutch Shell drilling rig used this summer in the Arctic is aground off a small island near Kodiak Island, where the ship, the Kulluk, appeared stable, said federal on-scene response co-ordinator Captain Paul Mehler.
"There is no sign of a release of any product," he said during a news conference at unified command centre at an Anchorage hotel.
When the storm eases and weather permits, the plan is to get marine experts on board the Kulluk to take photos and videos, and then come up with a more complete salvage plan.
The rig ran aground on Monday on a sand and gravel shore off an uninhabited island in the Gulf of Alaska.
Capt Mehler said the Kulluk was carrying about 143,000 gallons of diesel and about 12,000 gallons of lube oil and hydraulic fluid.
A US Coast Guard C-130 plane and a helicopter were used to fly over the grounded vessel yesterday. The severe weather did not permit putting the marine experts on board the drilling rig, which is near shore and being pounded by stormy seas.
Capt Mehler said there was a team of about 500 people working on a response to the situation "with many more coming".
The goal remained to get salvagers aboard the Kulluk and the ship refloated, he said.
A Shell official said the drilling rig was built with a double-sided hull of reinforced steel 3ins thick. It had recently undergone £180 million of improvements before being put into service for a short time this past summer in the Beaufort Sea off Alaska's north coast.
Stormy weather eased yesterday with waves 25 to 30ft and winds reduced to about 35mph. Winds were 70mph and waves had reached 50ft overnight, the National Weather Service said.
The drilling rig's difficulties go back to Thursday when it separated from a towing vessel south of Kodiak Island as it was being towed to Seattle for maintenance. The rig grounded on Monday night on a sand and gravel shore off the south-east side of Sitkalidak Island, an uninhabited island in the Gulf of Alaska.
Sean Churchfield, operations manager for Shell Alaska, said once the situation was under control an investigation would be carried out into the cause. The coastguard said it would also be investigating and its findings would be made public.
Ed Markey, the top Democrat on the House of Representatives Natural Resources Committee, said: "Oil companies keep saying they can conquer the Arctic, but the Arctic keeps disagreeing with the oil companies.
"Drilling expansion could prove disastrous for this sensitive environment."
The Kulluk was being towed by a 360ft anchor handler, the Aiviq, and a tugboat, the Alert. The vessels were moving north along Kodiak Island, trying to escape the worst of the storm, yesterday.
But at about 4.15pm, the drill ship separated from the Aiviq about 10 to 15 miles offshore. The tug boat crew guided the drill ship to a place where it would cause the least environmental damage and cut it loose. It grounded at about 9pm.