The U.S. Court of Appeals, in a 2-to-1 decision, has cleared the way for the federal government to accept more than $400 million in oil and gas leases in Alaska's Beaufort Sea -- a move that allows oil companies to begin preliminary exploration activity there.

The court's action vacated part of an order issued last January by U.S. District Judge Aubrey E. Robinson Jr. which blocked any lease sales, because the government failed to determine fully the environmental impact of the proposed drilling.

In a brief order issued late Tuesday, the appeals court lifted Robinson's ban on the lease sale, without explanation. The court said that a full written opinion on the merits of the case will be filed later.

Edward H. Comer, an attorney for the Alaskan natives who brought the case to court, said yesterday, however, that he has asked the appeals court to clarify whether it meant to allow the lease sale to go ahead or simply intended to permit preliminary exploration. Various observers express some confusion over the language and intent of the appeals court order.

Appeals court judges Malcolm R. Wilkey and George E. MacKinnon joined in the order which at least clearly allowed for early exploration activity in the Beaufort Sea.

When Robinson ruled last Jan. 22, he said that the Department of Interior had failed to fully assess the impact of the drilling projects on the well-being of both the bowhead whale and the Inupiate Eskimos, whose life style in Alaska's North Slope area is dependent on hunting whales and other wildlife.