Eddie Murphy refused to play Bill Cosby

Paige Butcher and Eddie Murphy attend the SNL 40th Anniversary Special at Rockefeller Plaza in New York. Photo / AP

Eddie Murphy refused to play troubled comedian Bill Cosby in a sketch during Saturday Night Live's 40th anniversary show.

The Beverly Hills Cop actor returned to the US comedy series after more than 30 years for the special.

Former SNL cast member and writer Norm Macdonald has revealed over a series of messages on Twitter.com that he tried to convince Murphy to play Cosby during the Celebrity Jeopardy segment.

But Murphy turned it down as he didn't want to poke fun at the star, who is facing a long line of sex abuse allegations.

"He knew the laughs would bring the house down. Eddie Murphy knows what will work on SNL better than any one," he tweeted.

"Eddie decides the laughs are not worth it. He will not kick a man when he is down.... Eddie Murphy, I realise, is not like the rest of us. Eddie does not need the laughs."

Cosby was played by SNL actor Kenan Thompson during the anniversary episode.

The anniversary episode was last Sunday.

- WENN