Alaska Gov. Steve Cowper said Friday he has tentatively approved the Soviet Union's offer to send oil-skimming equipment to Prince William Sound to assist in the cleanup of the worst oil spill in U.S. history.

Robert G. Poe Jr., director of the governor's office of international trade in Anchorage, confirmed that Morflot Freight Lines Ltd. has offered to send its oil skimmer-dredger Vaydagursky to the site for clean up. The ship, which is operated by an Italy-based affiliate of Morflot, is in Sakhalin, an island north of Japan. It could reach Prince William Sound in about four or five days, he said.

"We have given the Soviets tentative approval to start heading this way," said David Ramseur, a spokesman for Cowper. He said negotiations on Friday attempted to discover what the vessel would cost to use and the specifics on what the ship could perform.

Perhaps even more importantly, said Ramseur, "the slick is beginning to enter the Gulf of Alaska." The Soviet ship has been instructed to begin suctioning up any oil it may encounter en route to Prince William Sound.

Several companies have offered oil skimmers to Exxon Corp., but reports on Friday indicated the oil company had turned those offers down. Morflot, not knowing who to turn to with its offer, sent telexes to Exxon officials and the governor's office, sources said.

Joseph Storozuky, vice president of sales and marketing for Morflot Freight Lines Ltd., said early Friday, his company had received no response from Exxon.

Offers from other companies have surfaced. The oil-spill cleanup consortium called Clean Sound Cooperative in Seattle said it offered to send the largest self-propelled oil-skimming vessel in North America to the Alaska spill last Friday, but was turned down by Exxon representatives.

John Wiechert, manager of Clean Sound said he telephoned an Exxon executive in the Port of Valdez on the day of the spill to offer equipment including a 73-foot skimming vessel, a barge and other equipment that could have sailed to Valdez in four or five days.

A State Department official said that there were no governmental regulations that he was aware of that would prevent the Soviet ship from operating in Prince William Sound.