Actress Ariane Bellamar is using her Twitter feed to accuse actor Jeremy Piven of sexual assault on the set of his former HBO hit series “Entourage” and at the Playboy Mansion in Los Angeles. Bellamar took to Twitter on Monday with accusations against the actor, (the son of actors/drama teachers Bernie and Joyce Piven, founders of the Piven Theater and Workshop), who grew up in north suburban Evanston.

Tuesday night, Piven denied her claims. “I unequivocally deny the appalling allegations being peddled about me. It did not happen,” Piven said in a statement to Deadline.com. “It takes a great deal of courage for victims to come forward with their histories, and my hope is that the allegations about me that didn’t happen do not detract from stories that should be heard.”

Bellamar is a reality TV personality whose credits include the shortlived “Beverly Hills Nannies”  (cancelled in 2012). “Entourage” aired for eight seasons on HBO, beginning in 2004.

Ariane Bellamar | FACEBOOK

HBO said Tuesday’s press reports were the first it had heard of Bellamar’s allegations. “Everyone at HBO and our productions is aware that zero tolerance for sexual harassment is our policy,” said a statement from the cable channel. “Anyone experiencing an unsafe working environment has several avenues for making complaints that we take very seriously.”

CBS, the network which airs Piven’s current series “Wisdom of the Crowd,” said only, “We are aware of the media reports and are looking into the matter.”

Piven won three Emmy Awards and one Golden Globe Award for his portrayal of high-powered Hollywood agent Ari Gold on “Entourage.” (Gold was based in part on real-life Hollywood uber-agent Ari Emanuel, brother of Mayor Rahm Emanuel.)