Point Hope, Alaska (CNN) -- One of the ships that Shell Oil plans to use to drill in the Arctic slipped its mooring and drifted close to one of Alaska's Aleutian Islands, the latest in a string of incidents to arise around the controversial project.
The Noble Discoverer was about 175 yards from shore in Unalaska Bay when it slipped its mooring Saturday and drifted towards shore near Dutch Harbor, Coast Guard Petty Officer Sara Francis said.
"There are no reports of injuries, pollution and damage to the Noble Discoverer," she said Sunday night.
The incident raised concerns of a possible grounding near Dutch Harbor, though Francis said there was "no damage to the hull or evidence it ran aground."
The Noble Discoverer is one of roughly two dozen ships that Shell is sending to the Beaufort and Chukchi seas in the Arctic to drill exploration wells in the harshest climate in the world. Opinion: The stakes are huge Pete Slaiby, the vice president of Shell Oil in Alaska, told CNN recently the drilling in the arctic would be the "most complex, most difficult wells we've drilled in company history."
Proponents say if Shell finds oil with its Arctic drilling, it could create thousands of jobs; opponents -- Alaska's Inuit Eskimos and environmentalists -- say an oil spill could pollute the waters and damage the economy.
"Our subsistence for the winter, it all comes from the ocean, the fish and whale. It's going to ruin our ocean," 79-year-old Abagail Nashupuq of Point Hope told CNN recently.
Nashupuq has spent her entire life in the small northwest fishing village of Point Hope, which sits about 90 miles from where Shell plans to drill one of its exploratory wells in the Chukchi Sea.
Shell has been forced to postpone drilling, which was scheduled to begin this month, until August by an unexpected thick ice pack.
The delay cuts valuable time from Shell, which is operating under U.S. permits which require to stop drilling in the seas by the end of October.
Questions also were raised in June about the durability of one of Shell's underwater oil spill containment vessels in severe weather, which resulted in the vessel that was headed to one of the drilling sites to be temporarily held at port in Washington.
Opponents, primarily the Inuit and environmentalists, called for a review of the federal air permits that were issued to Shell Oil as part of its drilling plan.
Greenpeace, which has been leading a campaign against the drilling, issued a statement Sunday that questioned whether Shell could carry out the complicated plan if it was having problems with a ship's mooring.
Shell spokesman Curtis Smith said all indications pointed to the Noble Discoverer slipping anchor in soft ground, drifting only 100 yards toward shore.
"Shell quickly engaged one of its support vessels, the Lauren Foss, which safely towed the Discoverer back to its previous location," he said.
Francis, the petty officer, said the crew of the Noble Discoverer were interviewed.
"They did not feel any indication that the ship grounded," she said.
The Coast Guard plans an inspection of the interior of the ship's hull on Monday, the same day that Shell will use a diver to conduct a secondary inspection of the outer hull.
Smith said the anchor system used in the Arctic offshore drilling is "no way similar to the light anchor used in the harbor scenario."
Still, Slaiby promised a full investigation.
"Even a near miss is unacceptable. While an internal investigation will determine why the Discoverer slipped anchor, we are pleased with the speed and effectiveness of the mitigation measures we had in place," he said.
CNN's Greg Morrison contributed to this report
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