Larry Holmes, who lost a split decision in his bid to recapture the International Boxing Federation heavyweight title from Michael Spinks April 19, has filed official letters of protest to the IBF and the Nevada State Athletic Commission.

Holmes' attorney in Easton, Pa., Charles Spaziani, sent the letters and said he has asked Nevada's attorney general to look into the decision.

Judges Jerry Roth of Nevada and Frank Brunette of New Jersey scored the Las Vegas fight in Spinks' favor, 144-142 and 144-141, respectively. Joe Cortez of New York judged it 144-141, Holmes. Brunette and Cortez are IBF officials. Roth and referee Mills Lane were named by the state.

"It is unbelievable and unconscionable that your selection of Frank Burnet sic as a judge . . . could possibly be qualified . . . ," Spaziani's protest to the IBF read. " . . . I have asked the Nevada Athletic Commission to review the tapes of the fight and to look for improprieties or glaring errors on the scorecards. Several members of the Nevada Commission sat behind . . . Burnet and could not believe the manner in which he was scoring the fight."

Spaziani wrote the Nevada State Athletic Commission, "It would appear that the statements made by Larry Holmes prior to the bout might have affected the decision of the judges, which certainly would not be fair . . . "

After Holmes lost his title last September, he questioned the integrity of the judges. Following the latest loss, he again bitterly said he was robbed.

Fred Little, Nevada commission chief, said Holmes' protest will be discussed, and fight tape reviewed, when the five commissioners meet in May.

"But I doubt," he said, "if any decision will be made overturning the outcome. To my knowledge, that's never been done . . . not this late after a decision." BASKETBALL

The San Antonio Spurs, who ended in a 5-24 tailspin to a 35-47 season and were swept from the playoffs by the Los Angeles Lakers, fired coach Cotton Fitzsimmons. He had a year to go on a three-year contract for which he will be paid $275,000.

"Anybody who is let go is certainly disappointed, but I also understand the business," Fitzsimmons said. "This is year 16 as head coach in five cities for me in the NBA . . . I can deal with this."

Fitzsimmons is seventh in NBA coaching wins, 587 -- while losing 634 . . .

Clarence (Butch) Carter, at 27 a six-year NBA veteran, has returned to his alma mater, Middletown (Ohio) High School, as head coach . . . Paul Fuqua, 40, assistant coach at American University and formerly at Gonzaga High, his alma mater, has been named head coach at Mackin High. BASEBALL

Major league baseball will begin presenting today its side in the grievance filed by the players association over inclusion of drug testing clauses in long-term contracts. The union contends drug testing is a subject for collective bargaining.

This stage of the hearing, to be conducted at an undisclosed site before arbitrator Tom Roberts, is expected to last through Thursday. The union presented its side earlier this month. Rebuttals will be conducted next month . . .

Edward J. DeBartolo, the Youngstown, Ohio, developer, reportedly again is looking at the possibility of purchasing the Cleveland Indians, an idea endorsed by New York Yankees owner George Steinbrenner.

DeBartolo sought to buy the Chicago White Sox in 1980, but was rejected by the American League. DeBartolo told The (Cleveland) Plain Dealer he is holding off on whether to bid on the Indians until his advisers can thoroughly evaluate the team's financial condition.

DeBartolo, 67, folded his USFL Pittsburgh Maulers last year and his MISL Pittsburgh Spirit this month; still owns three race tracks, the NHL Pittsburgh Penguins and the Pittsburgh Civic Arena . . .

Mike Heath, the frustrated (batting .085) catcher for the St. Louis Cardinals, has apologized for an obscene gesture he made during Saturday's nationally televised game with the New York Mets.

Heath reacted to a razzing from a fan behind the Mets' dugout when he failed to catch a foul pop.

"I apologize," Heath said simply. HOCKEY

The Soviet Union won the World Hockey Championship a record 20th time -- surpassing Canada's 19 -- but had to struggle to deny Sweden's bid, 3-2, in the final at Moscow. Center Vyacheslav Bykov scored the winning goal with 4:44 to play.

Team Canada placed third this time, edging Finland, 4-3, on a goal by Tony Tanti with 2:34 left. GOLF

Fred Funk, the University of Maryland golf coach, shot 4-under-par 66 for a one-shot victory over George Graefe of Baltimore-Washington Golf Center in a Middle Atlantic PGA Pro-am at Rolling Road, Catonsville, Md. Dick Canney of Chantilly, 5 under after 10 holes, bogeyed three of his last four for 68.