* Sterling has not issued statement over alleged comments
* Auto dealer CarMax has pulled sponsorship of Clippers (Adds quotes and details)
April 28 (Reuters) - The National Basketball Association said it would make an announcement on Tuesday about its investigation into Los Angeles Clippers owner Donald Sterling as the fallout over his alleged racist comments began to pick up.
Sterling is being investigated by the NBA over racist comments he allegedly made that have since sparked widespread outrage in the United States.
The NBA said in a brief statement that a news conference would take place but gave no further details.
The NBA's announcement came shortly after auto dealer CarMax, a long-term sponsor of the Clippers, announced it was pulling its financial support of the team.
"CarMax finds the statements attributed to the Clippers' owner completely unacceptable. These views directly conflict with CarMax's culture of respect for all," CarMax said in a statement.
"While we have been a proud Clippers sponsor for nine years and support the team, fans, and community, these statements necessitate that CarMax end its sponsorship."
NBA commissioner Adam Silver said on Sunday that the league would "move extraordinary quickly in our investigation" after an audio recording was released of a racist rant allegedly made by Sterling.
The Clippers owner, who made his fortune in real estate, has not issued a statement but the alleged comments, which include telling a woman not to bring African-Americans to Clippers games, have drawn widespread criticism.
President Barack Obama weighed in, as did the Clippers players in a silent protest before Sunday's playoff game against the Golden State Warriors, while many Americans were calling for the NBA to send a clear message that such views will not be tolerated.
"This is a binding moment in the history of the NBA," said Sacramento Mayor and former NBA player Kevin Johnson, who is assisting the players union. "They (the players) are just outraged."
If the NBA investigation confirms that Sterling did make the comments, he could expect a harsh punishment. There have already been calls for the billionaire to be removed as an NBA owner but he could also face a lengthy suspension and fine.
Such punishment is not unprecedented in North American professional sport.
Marge Schott, the former president and majority owner of Major League Baseball's Cincinnati Reds, was suspended for two years for slurs against African-Americans and Jews.
Schott eventually sold her controlling interest in the team. (Reporting by Steve Keating Linden in Toronto; Editing by Julian Linden)
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