The Senate Appropriations Committee voted yesterday to cut off federal funds for processing or issuing oil and gas leases in wilderness areas starting Oct. 1, a move that environmentalists hailed as a major victory.

The vote climaxed several days of determined lobbying by Sen. Henry M. Jackson (D-Wash.) and other supporters of a popular wilderness protection bill that has run into opposition in the Senate Energy and Natural Resources Committee.

That committee's leaders have serious reservations about the wilderness protection bill, which would permanently prohibit oil and gas leasing on 33 million acres of unspoiled lands in the lower 48 states, and have not yet scheduled a vote on it.

The funding ban passed yesterday by the Appropriations panel would have essentially the same effect, except that it probably would expire in December.

The ban was introduced as an amendment to the continuing resolution to finance the government after Oct. 1. The House passed the same amendment last week.

The wilderness protection bill before the Energy Committee passed the House last month, 340 to 58, and is cosponsored by 54 senators, including 20 Republicans. Environmentalists have termed it "the most important public lands conservation bill of this Congress," and virtually every major environmentalist group is lobbying for its passage.

The bill is a direct response to Interior Secretary James G. Watt's announcement last year that he would consider granting leases in wilderness areas, a break with the policies of his predecessors, who routinely rejected them. Watt agreed to a moratorium on wilderness leasing until the end of this congressional session, calling on Congress to pass legislation to clarify the issue.

Hours before the funding ban was passed, the wilderness bill encountered grave skepticism in a hearing before the Senate Energy panel. Chairman James A. McClure (R-Idaho) and several other senators said they feared the protections in the bill would hinder the drive for energy independence, a view echoed in testimony from oil industry spokesmen and the Reagan administration.

"This is probably more charade than reality," said McClure, referring to the claims made by supporters of the measure, who contend it is needed to stop Watt from issuing oil and gas leases in pristine woodlands.

Jackson, who introduced the Senate bill, said yesterday he is convinced "the vast majority of the American public" supports it. He said the measure would not hinder the search for energy since it would ban leasing in a relatively small area -- less than the 35 million acres covered by oil and gas leases that the Interior Department plans to issue this year.

The bill's chances of reaching the floor, amid the crush of other legislation and the rush toward adjournment, are considered slim.

The administration, in testimony by Assistant Agriculture Secretary John R. Crowell Jr., essentially opposed the bill as written. Crowell called for amendments that would release millions of acres of forest lands from consideration for the wilderness system. The Jackson bill would protect these lands until Congress votes to release them or until a study recommends their release.