An inaccurate map that mislocated a marine sanctuary may have caused a U.S. Navy minesweeper to run aground on a coral reef in the Philippines this week, the Navy said Saturday.

All 79 officers and crew of the USS Guardian were taken off the ship for safety reasons after it struck the reef with its bow at 2 a.m. Thursday. The Navy's Pacific Fleet, based in Hawaii, said Saturday that its ships along with several support vessels continued to conduct salvage operations that minimize environmental effects to the reef.

The Navy said in a statement that a review of Digital Nautical Charts, which are used for safe navigation by all U.S. Navy ships, found they contained inaccurate data and may have been a factor in the Guardian's grounding. As a result, Navigator of the Navy Rear Adm. Jonathan White released precautionary guidance to all Pacific Fleet ships, saying that "initial review of navigation data indicates an error in the location of Tubbataha Reef" in the Philippines.

"While the erroneous navigation chart data is important information, no one should jump to conclusions," said Pacific Fleet spokesman Capt. Darryn James. "It is critical that the U.S. Navy conduct a comprehensive investigation that assesses all the facts surrounding the Guardian grounding."

The Avenger-class ship had just completed a port call in Subic Bay, a former American naval base west of the capital, Manila, and was en route to Indonesia and then on to East Timor to participate in a training exercise when it hit the reef, about 128 kilometers (80 miles) southeast of Palawan Island.

The World Wide Fund for Nature Philippines said that according to an initial visual inspection, the 68-meter- (74-yard-) long, 1,300-ton Guardian damaged at least 10 meters (yards) of the reef, which UNESCO designated as a World Heritage Site. It is part of Southeast Asia's Coral Triangle, a huge stretch of ocean that contains most of the world's coral species, reefs, and more than 3,000 species of fish.

Angelique Songco, head of the government's Protected Area Management Board, said the government imposes a fine of about $300 per square meter (yard) of damaged coral, plus other fees.

In 2005, the environmental group Greenpeace was fined almost $7,000 after its flagship struck a reef in the same area.

Songco blamed the Guardian for turning away park rangers who wanted to board the minesweeper, but the Navy said it was cooperating with the Philippine government, a key U.S. defense ally.

Presidential spokeswoman Abigail Valte said the government will observe the law governing the Tubbataha Reef, but right now "the primary concern is extricating the ship out of the reef with minimal damage."

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Associated Press writer Audrey McAvoy in Honolulu, Hawaii, contributed to this report.