Onyewu to sue over racial insult
Van Damme has denied the allegations and said he is not a racist. The Brussels prosecutor's office was not available for comment.
"My client is taking a stand and has asked the prosecutor's office to investigate whether Van Damme should face criminal proceedings," Dupont said.
"It is not a question whether Van Damme is racist. The issue is that these slurs are still used on the pitch, and are being used because they know it hurts."
The incident occurred on May 21 during the opening leg of the two-game series between Liege and Anderlecht.
During the 1-1 draw in Brussels, Onyewu said he had alerted the referee about the racist comment,but the match was not interrupted. Dupont said Onyewu had threatened to leave the pitch but his team mates had convinced him to stay.
Liege beat Anderlecht 1-0 in the return leg, giving the 27-year-old his second consecutive Belgian league title.