Just days after his final send-off, one of Muhammad Ali's former girlfriends has made sensational claims about his sex life. Barbara Mensah says she has amateur sex tapes featuring the boxing legend, and names him as the father of her daughter.

Speaking to the Sunday People, she said that she knows the value of the footage, which she hopes to sell for $100,000 (£70,000). "No one has anything like this. I'd like to get as much as I can for it," she said. Mensah and Ali met in 1964 when she was 19-years-old, and they had a 20-year relationship.

Of the alleged tapes, she said: "There would be Ali and a few of his guys and then about a dozen or more girls. All of them were stunning. Muhammad couldn't keep away from a pretty girl whether he was married or not. The tapes show them having sex. They used to call them gumbo parties – it was a mix of everything."

To make it easy to secure a deal, Mensah has already made inquiries about getting the old film converted to DVD. The Texas native also claims that her 35-year-old daughter, Kiiursti Mensah Ali, is the product of the 20-year affair that she had with the three-time world heavyweight champion. She alleges that a 1988 paternity test confirmed that he is the father. Although she has taken his last name, he is not listed on her birth certificate.

Kiiursti previously claimed that Ali's fourth wife Lonnie was preventing her from building a relationship with her father. "Muhammad Ali is my dad – but everything changed the moment he married her," Kiiursti told the Mirror. He stopped coming to see me. As the years went by, he got sicker and sicker. She stopped him having a relationship with me. It's been devastating."

Ali, who battled with Parkinson's Disease for more than three decades, passed away on 3 June, at a hospital in Phoenix, Arizona where he had been admitted a day earlier following a respiratory condition. He was 74.

His funeral was held his hometown of Louisville, Kentucky, on 10 June and attended by thousands fans and famous names, including former US president Bill Clinton, actor and comedian Billy Crystal, British heavyweight champion Lennox Lewis and actor Will Smith, who played the boxer in a 2001 biographical film.

After attending the Olympian's Muslim prayer service in Louisville, Kentucky, Mensah paid tribute to him in a Facebook post. "It really, really hurts and only time will ease the pain R.I.P until we meet again," she wrote. "I'm so glad I came to say goodbye to my love you were always there for me I never would have miss your home going for the world."