The animal-loving widow of Richard Pryor banned Chris Rock from portraying the late comedy icon on the big screen after he made a joke about dog fighting, according to reports.

The Head of State star was among the frontrunners to land the main role in a new Pryor biopic, but he allegedly lost the part after jokingly defending shamed American football star Michael Vick, who recently served time for running an illegal dog-fighting ring.

During a recent appearance on U.S. TV's The Jay Leno Show, Rock said, "What the hell did Michael Vick do? Pitbulls ain't (sic) even real dogs! Dogs have never been good to black people!"

The quip offended Pryor's wife Jennifer, who serves as the director of animal rescue group Pryor's Planet, and she made sure Rock's throwaway comments cost him the movie job.

In an open letter to the star, Jennifer fumes, "For your information, Chris, what Michael Vick did was to torture, drown, electrocute and murder dogs all for fun and for profit! He went to prison for felony animal cruelty! That's what he did!

"These types of comments only encourage abuse and misunderstanding of this breed, as well as actual dog-fighting. Clearly this part of your latest stand-up routine would not make Richard laugh!"

Fellow funnyman Marlon Wayans is reported to have landed the coveted role in Richard Pryor: Is It Something I Said?, which is expected to hit cinemas in 2011.

Pryor, who founded Pryor's Planet before his death, passed away in 2005 from a cardiac arrest, aged 65.