St. Louis, Missouri - Open AI CEO Sam Altman denied on Tuesday allegations from his sister Annie Altman, who has filed a legal complaint accusing him of childhood sexual abuse.

According to the lawsuit launched in Missouri, Annie – who is nine years younger than Altman – alleges the assaults took place "several times a week" from 1997, when she was three, until 2006.

In response, the billionaire posted a letter on X co-signed by his mother and two brothers that read: "...Annie has made deeply hurtful and entirely untrue claims about our family, especially Sam."

"Our family loves Annie and is very concerned about her well-being. Caring for a family member who faces mental health challenges is incredibly difficult," they wrote.

Altman shot to global fame with OpenAI's launch ChatGPT in 2022, which ignited a race to advance AI research and development.

The Altman family said that they have tried to help their daughter and sister, covering her expenses and guaranteeing her "monthly financial support, which we expect to continue for the rest of her life."

"Despite this, Annie continues to demand more money from us," they said, pointing out that they have decided to respond publicly following Anne's legal complaint filed on Monday, and after years of tension.

"The worst allegation she has made is that she was sexually abused by Sam as a child," said the family.

"Her claims have evolved drastically over time. Newly for this lawsuit, they now include allegations of incidents where Sam was over 18.

"All these claims are utterly untrue."

A New York Magazine profile of Altman in 2023 described her as an artist suffering from depression and the growing rift with her family, and supporting herself mainly through online sex work.