The House Interior Committee, inviting open confrontation with Interior Secretary James G. Watt, invoked a rarely used emergency provision of federal law yesterday to declare Montana's Bob Marshall Wilderness Area off limits to oil and gas development.

Watt has reportedly declared his intention to open more public land, including wilderness areas, to mineral development. Before becoming interior secretary he had represented an exploration company seeking to set off 5,400 dynamite charges within the Bob Marshall area -- a request that has so far been held up by the U.S. Forest Service.

"The Bob Marshall may be the greatest single wilderness area in the country," said Rep. Pat Williams (D-Mont.), who led the committee fight to protect the area. "It straddles the continental divide, and includes the watersheds of two great rivers, the Columbia to the west and the Missouri to the east. It contains 70 percent of the grizzlies left in the United States and the largest big-horn sheep herd in the country."

The committee's 23-to-18 vote, in which all the Republicans voted no, is final; full House or Senate approval is not required. However, Watt could contest its constitutionality in court.

An Interior Department spokesman said the secretary, en route yesterday to his daughter's wedding, was unavailable for comment.

The 1.5 million acres of the Bob Marshall are part of the Overthrust Belt, a potentially rich area for oil and gas development that spans parts of Montana, Wyoming, Utah and Colorado. Companies have filed 343 applications for mineral leasing in the Bob Marshall.

However, the area represents a relatively small portion of the Overthrust Belt, where about 7 million acres of non-wilderness public lands are involved in pending lease applications.Rough estimates put Bob Marshall's mineral potential at 40 days' worth of natural gas, at the nation's current consumption level.

"The resource here is not oil -- it's natural gas," Rep. Williams said, "Americans are now reducing their dependence on natural gas and we have a plentiful supply. Natural gas wells are capped all over the West waiting for the price to rise."

During two hours of heated debate in committee, Rep. Ron Marlenee (R-Mont.) said the emergency procedure subverts the intent of the law and sets a bad precedent for legislation without full congressional approval. No emergency exists, he said, because the lease applications require an environmental impact statement -- a contention Williams disputes.