About 108 offshore oil and natural gas platforms destroyed by the hurricanes.

WASHINGTON (Reuters) - A total of 108 low producing oil and natural gas offshore platforms were destroyed by hurricanes Rita and Katrina and some of the other 53 heavily damaged platforms could be offline until next year, the U.S. Interior Department said on Tuesday.

The destroyed platforms likely will not be rebuilt, Interior Secretary Gale Norton told reporters, adding that repairing damage elsewhere would run into the "billions of dollars."

In a briefing on the damage done by the hurricanes, the department also said that 90 percent of crude oil production in the Gulf of Mexico is still shut-in and 72 percent of offshore natural gas production is still offline.

Norton said the destroyed platforms account for about 1.7 percent of oil output in the Gulf of Mexico and 0.9 percent of natural gas production.

Repairs to platforms with major damage could run into next year, while restaffing unmanned rigs that escaped damage so they can operate again could take another 10 days, she said.