NBA commissioner David Stern dismissed allegations from a former referee at the center of a gambling scandal that the 2002 playoff series was rigged by league referees and officials, calling the claims baseless.

"He turned on basically all of his colleagues in an attempt to demonstrate that he is not the only one who engaged in criminal activity," Stern said of Tim Donaghy before Game 3 of the NBA finals in Los Angeles on Tuesday. "The U.S. attorney's office, the FBI have fully investigated it, and Mr. Donaghy is the only one who is guilty of a crime."

The allegations about the 2002 series were contained in a letter filed by a lawyer for Donaghy, who pleaded guilty last year to felony charges alleging he took cash payoffs from gamblers and bet on games himself. Donaghy, 41, faces up to 33 months in prison at sentencing on July 14.

Without identifying anyone or naming teams, Donaghy also claimed the NBA routinely encouraged refs to ring up bogus fouls to manipulate results but discouraged them from calling technical fouls on star players to keep them in games and protect ticket sales and television ratings.

"If the NBA wanted a team to succeed, league officials would inform referees that opposing players were getting away with violations," the letter said. "Referees then would call fouls on certain players, frequently resulting in victory for the opposing team."

Donaghy's lawyer has sought to convince a federal judge in Brooklyn that Donaghy, of Bradenton, Fla., deserves more credit for coming forward before he was charged to disclose behind-the-scenes misconduct within the NBA. The letter, filed Monday, suggests prosecutors have hurt Donaghy's chances for a lesser prison term by downplaying the extent of his cooperation.

Both Donaghy's attorney, John Lauro, and prosecutors declined comment.

The league said the scandal was limited to Donaghy and two co- defendants, both former high school classmates who also pleaded guilty to gambling charges.

"The NBA remains vigilant in protecting the integrity of our game and has fully cooperated with the government at every stage of its investigation," Richard Buchanan, NBA executive vice president and general counsel, said in a statement. "The only criminal activity uncovered is Mr. Donaghy's."

Larnell McMorris, a spokesman for the NBA referees union, said in a statement that Donaghy "has had honesty and credibility issues from the get-go."

Donaghy's letter said that in the first of several meetings with prosecutors and the FBI in New York in 2007, he named names while describing "various examples of improper interactions and relationships between referees and other league employees, such as players, coaches and management." For example, it said, referees broke NBA rules by hitting up players for autographs, socializing with coaches and accepting meals and merchandise from teams.

In one of several allegations of corrupt refereeing, Donaghy said he learned in May 2002 that two referees known as "company men" were working a best-of-seven series in which "Team 5" was leading 3-2. In the sixth game, he alleged they purposely ignored fouls made by opponent "Team 6" and made phantom calls putting its players at the free-throw line.

"Team 6" won the game and came back to win the series, the letter said.