A Hollywood bookstore owner who has been auctioning off Academy Award Oscar statuettes since last year is planning still another sale, and the Academy of Motion Picture Arts & Sciences wants to stop him.

Malcolm Willitts, who has already sold six genuine Oscars to the highest bidders, Malcolm Willitts, claims he is only bringing what he says is the common practice of selling the statuettes into the open."Oscars have been sold for 60 years at garage sales and in pawn shops," said Willitts, owner of the Collectors Book Store, in the heart of Hollywood.

But the Academy considers Willitts' auctions a sacrilege. Its attorney has written a letter threatening Willitts with a breach of Academy regulations if he follows through with his next auction.

Willitts announced late last year that he is accepting telephone and mail bids for the Oscar presented to the late Mike Todd for "Around the World in 80 Days," which was named best picture of 1956.

"I think it could go for as high as $100,000," Willitts said. "You never know at an auction. But in this case it could be that high, because Mike Todd was married to Elizabeth Taylor at that time, and he died tragically the year after he got the Oscar."

John B. Quinn, a Los Angeles attorney representing the Academy, sent Willitts a letter Jan. 11 warning him that he would be "subject . . . to liability" if he follows through with the auction.

Quinn also enclosed a copy of a waiver, signed by Todd, which contains fine print intended to discourage any thought of selling the statuette.

The waiver reads:

"I agree to comply with your rules and regulations respecting its use and not to sell or otherwise dispose of it, nor permit it to be sold or disposed of . . . without first offering to sell it to you for the sum of $10."

It goes on to specify that the terms apply not only to Todd, but also to his "heirs, legatees, executors, administrators, estate, successors and assigns."

Attempts to reach Quinn for comment were unsuccessful.

Willitts has ignored previous Academy threats and auctioned or sold six other Oscars beginning last March.

The first auction saw one bidder pay $15,760 for the Oscar awarded to Arthur Freed for "An American In Paris," the best picture of 1951.

Willitts then sold the best actor Oscar presented to Marlon Brando for 1954's "On the Waterfront," an Oscar for special effects for the 1938 feature, "Spawn of the North," the 1961 Academy Award presented to a Yugoslavian cartoon called "Ersatz," an art and set decoration Oscar for the 1958 musical "Gigi" and an interior decoration Oscar for the 1941 film "How Green Was My Valley."

The 1941 Oscar has brought the highest price to date, $17,715, while the Brando Oscar was sold for $13,000 and the others for between $7,000 and $10,000.

Willitts said he has taken a 15 percent cut of each sale, with a smaller percentage going to a publicist and the majority going to the statuette's donor.

In the Todd case, Willitts said the Oscar was donated by the late producer's grandson.

"He received it as a wedding present," Willitts said. "But many times these Oscars get into people's hands who don't even remember the original recipients. It doesn't mean as much to them."

Only once has the Academy successfully prevented Willitts from completing an auction. It sought and received a temporary restraining order last August that stopped the auction of an honorary Oscar originally presented to 20th Century Fox production chief Darryl F. Zanuck for the introduction of the CinemaScope wide-screen process.

"Zanuck gave it to his secretary, and 35 years later she put it in our auction," Willitts said. "Both the Academy and Fox claimed Zanuck did not have the right to give it away."