Bill Cosby defended by screen wife Phylicia Rashad

Phylicia Rashad and Bill Cosby, pictured in 2002, played wife and husband on The Cosby Show

The actress who played Bill Cosby's wife in The Cosby Show has said allegations of historical sex offences against her former co-star are part of a campaign to keep him off TV.

Phylicia Rashad played Clair Huxtable on the hit 1980s and '90s sitcom.

"Someone is determined to keep Bill Cosby off TV," she told the Showbiz 411 website. "And it's worked. All his contracts have been cancelled."

But Cosby is due to return to the live stage in Canada on Wednesday.

He is due to perform three shows in Ontario, beginning in Kitchener. It will be his first live performance since November.

Protests are due to be held outside the Ontario shows, and some ticket holders have said they will stay away or heckle the star.

Disruption warning

A statement issued on behalf of Cosby read: "Dear Patrons: we have been advised that there may be attempts to disrupt tonight's performance.

"If a disruption occurs, please remain calm until the matter is resolved and do not confront the person making the disruption."

Cosby has been accused of sexual assault by at least 15 women. He has denied the claims, calling them "fantastical" and "uncorroborated". He has not been charged.

Defending her former co-star, Rashad said of the alleged victims: "Forget these women... What you're seeing is the destruction of a legacy. And I think it's orchestrated.

"I don't know why or who's doing it, but it's the legacy. And it's a legacy that is so important to the culture."

The accusations have led US network NBC to scrap a proposed TV project with the comedian, while streaming service Netflix has postponed a special show with Cosby.

US network TV Land pulled repeats of The Cosby Show, in which the star played Dr Cliff Huxtable from 1984 to 1992.

Ten performances on Cosby's North American tour have also been called off.