Lawyers for Bill Cosby have demanded a Pennsylvania court drop the first criminal sexual assault charge filed against the disgraced comedian since dozens of women publicly accused him of abuse.

His lawyers filed the petition in Montgomery County on Monday, asking the court to dismiss the charge that forced the megastar turned pariah to post bail for $1 million on December 30. He is next due in court on February 2.

The petition demands the court throw out the charge because it violates a 2005 agreement that Cosby would never be prosecuted over allegations of assault made by Andrea Constand, a former employee of Temple University in Philadelphia.

The newly elected district attorney "repudiated the agreement" and Cosby was "wrongfully charged," his lawyers wrote.

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They said an "inexcusable" 10-year delay since the alleged 2004 incident had also "greatly prejudiced Mr Cosby."

The former TV legend has lost his eyesight and "with it his ability to identify the physical appearance of witnesses and accusers as well as review other pieces of evidence," the petition stated.

"Justice requires that the court dismiss the charges at this stage."

A stony-faced Cosby appeared in court in Elkins Park, in the Philadelphia area, on December 30 in connection with the aggravated indecent assault charge but did not enter a plea.

Constand says Cosby assaulted her at his Philadelphia suburban home in 2004.

If found guilty, the 78-year-old - who has surrendered his passport to the court - could face up to 10 years in prison and a $25,000 fine.

More than 50 women have publicly claimed abuse by the pioneering black comedian, who attained his greatest fame for his role as a lovable obstetrician and pater familias in the hit 1980s sitcom The Cosby Show.

But his attorneys repeatedly deny any wrongdoing by the veteran TV actor whose career spanned four decades.

Prosecutors say the charge stems from new evidence in the case that came to light in July, prompting the reopening of the investigation.

Statutes of limitations have prevented most of the women who have accused the comedian of sexual assault from taking legal action.

In the Pennsylvania case, the statute of limitations was set to expire early next year.

-AFP