Richards has said he is "really busted up" over the incident

The 57-year-old was filmed directing a racist insult at a heckler during a stand-up comedy show in Los Angeles.

Having apologised on television, he has now employed New York publicist Howard Rubenstein to convey his contrition.

According to Mr Rubenstein, the actor "wants to heal the tremendous wound he's inflicted on the American public".

To this end, the PR expert arranged calls between the actor - who played the eccentric Cosmo Kramer in Seinfeld - and two civil rights leaders, the Reverends Jesse Jackson and Al Sharpton.

"Michael apologised profusely," Mr Rubenstein told the Associated Press. "I think it was a positive discussion."

'Volatile and dangerous'

Speaking to the same news agency, Rev Jackson said the actor needed "race sensibility training and some psychiatric help".

"His anger is volatile and dangerous to himself and others."

"But the culture that's producing this kind of animosity toward blacks must be addressed," he added.

Richards (r) played the eccentric Cosmo Kramer in Seinfeld

"We have to evaluate the use of the N-word and categorise it as hate speech, no matter who uses it."

Richards was performing at the Laugh Factory in Los Angeles a week ago when he insulted two black audience members for disrupting his routine.

He claimed his remarks were fuelled by anger, not bigotry.

Reports subsequently surfaced that Richards had shouted anti-Semitic remarks during a previous stand-up comedy routine in April.

Mr Rubenstein confirmed these reports but said the actor had been "playing a part" at the time.