Russell Simmons, the mogul who founded iconic hip-hop label Def Jam as well as a host of other companies, has stepped down from them after a fresh sexual assault allegation was made against him.

The screenwriter Jenny Lumet, whose credits include Rachel Getting Married and The Mummy, and whose father is acclaimed director Sidney Lumet, accused Simmons in a column for Variety. She recalls that “circa 1991”, after Simmons offered her a ride back to her house, he then locked the car doors and had his driver take them to his apartment, where he allegedly coerced her into sex.

Simmons has responded to the article with a statement, saying: “While her memory of that evening is very different from mine, it is now clear to me that her feelings of fear and intimidation are real. While I have never been violent, I have been thoughtless and insensitive in some of my relationships over many decades and I sincerely apologise.”

Allegation … Jenny Lumet at a New York film event earlier this year. Photograph: Roy Rochlin/FilmMagic

He added that he would step aside from his numerous companies, grouped as Rush Communications – which include clothing, health and media brands, some carrying the “Def” name; Simmons sold Def Jam itself to Universal in 1998. “I don’t want to be a distraction so I am removing myself from the businesses that I founded,” he said. “I will step aside and commit myself to continuing my personal growth, spiritual learning and above all to listening.”

Simmons was accused of sexual assault earlier this month by model Keri Claussen Khalighi, in an incident also in 1991, and involving disgraced Hollywood director Brett Ratner. Simmons denied the assault, saying that “everything that occurred between Keri and me occurred with her full consent and participation”.