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A US Navy minesweeper has run aground in a protected marine sanctuary in the Philippines.
The USS Guardian ran aground on the Tubattaha Reef on Wednesday night "during normal transit", it said.
The extent of the damage to the ship and the cause of the accident was still not known, it added.
"The government of the Philippines was promptly informed of the incident and offered to assist the US Navy," it said.
The US Navy said on its website that the 224-foot vessel is based in Sasebo, southern Japan but it was not known what the ship was doing in the area when the incident happened.
Located in the Sulu Sea about 80 miles southeast of the western island of Palawan, Tubattaha Reef is a protected sanctuary that is popular with divers.
It has walls of corals, and a very diverse ecosystem that environmentalists say rivals that of the Great Barrier Reef in Australia.
The US embassy statement did not say whether any coral was damaged, although it said there were no immediate reports of fuel or oil leaks.
All its crew members were also safe, it added.
The Philippine military also confirmed the grounding Thursday, but it was too early to say whether coral was damaged.
"The most probable cause is mis-navigation," said Major Oliver Banaria, a military spokesman in Palawan.
Washington considers the Philippines a major non-NATO ally in Asia. It played host to some of the US military's biggest bases in Asia until 1992, when the last troops pulled out after the Senate voted to end lease agreements.
Manila ratified a visiting forces agreement with the United States seven years later, paving the way for large-scale joint military exercises.
Some 600 US forces have been operating in the southern Philippines since 2002 to train local troops against Al Qaeda-linked militants.
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