LOS ANGELES (AFP) - The commanding officer and three crew of a United States (US) minesweeper which ran aground on a protected coral reef in the Philippines have been relieved of their duties, the US Navy said on Thursday.

A statement from the US Pacific Fleet in Hawaii said an initial investigation had found that the commander of the USS Guardian and three others had failed to "adhere to standard US Navy navigation procedures".

"The US Navy has the highest accountability standards and all four sailors were relieved by Rear Admiral Jeffrey Harley due to their role in the grounding and a loss of confidence," a statement said.

The minesweeper ran aground on Tubbataha in a remote part of the Sulu Sea on Jan 17, damaging a section of the reef, a United Nations Educational, Scientific and Cultural Organisation (Unesco) World Heritage site known for its rich marine life.

The incident sparked widespread condemnation across the Philippines, a former US colony.

The US government has apologised for the accident, which it initially blamed on faulty maps. The Philippines has said it would impose fines.

The US government agreed to scrap and dismantle the ship - valued at around US$277 million (S$343 million) - after fears that towing it to deeper waters would inflict more damage on the reef.

Salvage teams removed the last piece of the 68m USS Guardian from the damaged reef on March 29.