Mason confirmed in a statement Monday night that he had been terminated, but disputed that he had been fired because of allegations of corruption, as TMZ reported.
"I was terminated by BIG3 in retaliation for legal claims which I made last week in a letter sent by my attorneys to BIG3 Basketball alleging that the League had breached my employment agreement," Mason said in his statement.
TMZ reported that the firing involved Mason's connection to a pair of Qatari investors who were allegedly cheating the league.
In his statement, Mason said the work environment at the BIG3 was "hostile and racist" and accused BIG3 co-founder Jeff Kwatinetz of a "malicious, defamatory campaign of disparaging me."
A spokesperson for Kwatinetz and Ice Cube told TMZ, "Mason's claims do not require a dignified response beyond the fact that they are preposterous and false."
The BIG3 is a 3-on-3 basketball league founded by actor/rapper Ice Cube that features mostly retired NBA players. After last year's inaugural season it will return this summer, featuring former players Metta World Peace, Amar'e Stoudemire, Glen "Big Baby" Davis, Nate Robinson and Baron Davis.
Ice Cube will act as commissioner until a new director can be found, TMZ reported.
Mason, who played for seven NBA teams during an 11-year career, was also deputy executive director of the National Basketball Players Association.