John Nash, the mathematician upon whose biography the Oscar-nominated film A Beautiful Mind is based, has denied allegations that he is gay.

Gay activists claimed that homosexual experiences described by Nash's biographer were left out of the film.

The film which is based on the book: A Beautiful Mind: The Life of the Mathematical Genius and Nobel Laureate John Nash by Sylvia Nasar contains numerous references to Nash's homosexuality, including details of his 1954 arrest for indecent exposure and making a pass at another man in a public toilet.

Critics are upset that the film makes no mention of any his alleged homosexuality.

The Nobel laureate, whose battle with schizophrenia was dramatized in the movie starring Russell Crowe, will appear in a CBS 60 Minutes interview to dispute allegations that the film was "sugar-coated."

In the television interview, Nash denies being homosexual but refuses to discuss it further, saying only, "I've learned that it's better that I don't talk about it." Alicia Nash, his wife, backs him up. "I've known him since I was 20 and that's just not true ... I should know."

A source close to the film said that references to homosexuality were omitted to build a stronger romantic storyline between Crowe and co-star Jennifer Connelly, according to the Drudge Report.

The source said: "The homosexual stuff found in the book got in the way. Besides, American audiences don't care to see Russell Crowe getting it on with a man! It would just kill us at the box office."

A spokesperson for Gay & Lesbian Alliance Against Defamation, the gay rights group, said: "It is rather alarming in this day and age that Universal studios and Dreamworks would find same-sex love too offensive to be depicted in a major motion picture."

A Beautiful Mind has been nominated for eight Academy Awards.