(CNN) -- The U.S Navy minesweeper that grounded on a Philippine reef last week has taken on water and sustained too much damage to be towed off, the Navy says. "It's got hull penetrations in several places, and there is a significant amount of water inside the ship," Rear Adm. Tom Carney said at a briefing Thursday. The Navy said it will use ship-borne cranes and heavy-lift vessels to lift the minesweeper, the USS Guardian, off the Tubbataha Reef. "As the crane ships arrive, we will take items off the Guardian to lighten the weight of the ship so we are able to remove it from the reef," Carney said. "The option that we had hoped to tow the ship off the reef is not available. The ship is too badly damaged."
@highlight
The USS Guardian has several holes in its hull, admiral says
@highlight
The 1,300-ton minesweeper will have to be lifted onto a barge
@highlight
The ship damaged more than 10,000 square feet of the Tubbataha Reef
@highlight
The reef is a UNESCO World Heritage Site
"It is critical that the U.S. Navy conduct a comprehensive investigation that assesses all the facts and circumstances surrounding the @placeholder grounding."