* Sterling has not issued statement over alleged comments
* Several companies pull sponsorship of Clippers
* Lengthy ban widely seen as the likeliest outcome (Adds detail, quotes, further sponsors withdrawing)
LOS ANGELES, April 28 (Reuters) - The National Basketball Association faced mounting pressure on Monday to impose a harsh punishment on Los Angeles Clippers owner Donald Sterling for his alleged racist comments as several of the team's sponsors pulled their backing.
Sterling is being investigated by the NBA over comments he allegedly made that have since sparked widespread outrage in the United States, and the league will hold a news conference in New York City on Tuesday to discuss developments.
The NBA's brief announcement on Monday came shortly after some of the team's sponsors began withdrawing their financial support of the Clippers while Sterling's own family distanced themselves from him.
Auto dealer CarMax, a nine-year sponsor of the Clippers, was first to announce it was ending its association and was followed by Virgin America, State Farm, Kia Motors America, music mogul P. Diddy's water brand, AQUAHydrate, Red Bull and Yokohama Tire.
"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.
State Farm said it was "pausing" its relationship with the Clippers while closely monitoring the situation.
AQUAHydrate posted on its Twitter account: "In the wake of Sterling's alleged intolerable comments we are suspending our Clippers sponsorship until the NBA completes its investigation."
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 any public statements 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 are calling for the NBA to send a 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."
Five-time NBA champions Kobe Bryant, whose Lakers share their home venue with the Clippers at Staples Center in downtown Los Angeles, said of Sterling on Twitter: "No. He should not continue owning the clippers. #nochance #noway #nohow."
If the NBA investigation confirms that Sterling did make the racist 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.
A lengthy suspension is widely seen as the likeliest outcome, according to experts, though the NBA is not expected to impose any punishment on Sterling until its investigation into the alleged comments is completed.
'FAMILY IS DEVASTATED'
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.
Sterling's estranged wife Shelly released a statement on Monday condemning the comments attributed to her husband.
"Our family is devastated by the racist comments made by my estranged husband. My children and I do not share these despicable views or prejudices," she said.
"We will not let one man's small mindedness poison the spirit of the fans and accomplishments of the team in the city we love. We are doing everything in our power to stand by and support our Clippers team."
The Clippers are due to host Golden State on Tuesday in the fifth game of their best-of-seven first-round playoff series.
The teams are currently tied at 2-2 but the series has been overshadowed by the race row. The fallout has even impacted the pre-game entertainment for Tuesday's game.
R&B recording artist Tank, who was scheduled to perform the U.S. national anthem, has withdrawn in protest.
"As an African American man and artist, I must take a stand on a matter that is so deeply personal to me," he told TMZ.com. (Additonal reporting by Julian Linden in New York and Steve Keating in Toronto; Editing by Frank Pingue)