A US Navy minesweeper stuck on a coral reef in a Unesco heritage site off the Philippine coast is badly damaged and taking in water, officials say.The USS Guardian struck the reef in the Sulu Sea south-east of Palawan island last Thursday after completing a port call at the former Subic Bay base.
US officials say a salvage operation could take weeks to complete.
The reef is in the Tubbataha National Marine Park, designated a World Heritage Site by Unesco.
There had been hopes that the ship could simply be towed off the reef, but officials said the vessel was too badly damaged for that and that the first priority was to pump fuel out of the ship as it was being battered by rough waters.
"It's got hull penetrations in several places, and there's a significant amount of water inside the ship right now," said Rear Adm Thomas Carney, commander of the Navy's Logistics Group in the Western Pacific.
He said the salvage operation would be "a very deliberate complicated process" which could involve two or more US Navy ships and take up to two weeks to complete.
All 79 of the ship's crew were transferred to a smaller vessel for safety reasons. No-one was hurt in the incident.
According to Unesco, the area the ship is grounded is a "unique example of an atoll reef with a very high density of marine species". Part of it serves as a nesting site for birds and marine turtles, it says.
Divers from the Philippine coast guard have been measuring coral damage at the site.
The Philippine government has said it wants to fine the US Navy for unauthorised entry into the protected reef area and for any damage incurred to the protected site.
Rear Adm Carney expressed his "deepest regret" for the incident and said that an investigation will consider the causes for the grounding and assess damage to the reef.
Officials from the Philippines and the US - which have close military ties - can then discuss claims and compensation, he added.
Environmental group Greenpeace was fined almost $7,000 (£4,380) in November 2005 for damaging a coral reef in the park after its flagship Rainbow Warrior II ran aground.
Greenpeace paid the fine but blamed the accident on outdated maps provided by the Philippine government.