Actor and comedian Bill Cosby has sued seven women, saying they lied when they accused him of sexual assault.

The countersuit, filed in a US district court in Springfield, Massachusetts, contends that the women defamed his “honourable legacy and reputation” by accusing him of sexual misconduct.

More than 50 women have come forward to accuse the actor, best known for his role in the 1980s television hit The Cosby Show, of sexually assaulting them after plying them with drugs or alcohol.

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Cosby has repeatedly denied wrongdoing and has never been criminally charged.

Many of the alleged incidents occurred decades ago and the statute of limitations for prosecuting them has long run out.

“Mr Crosby states plainly that he neither drugged nor sexually assaulted the defendants, and that each defendant has maliciously and knowingly published multiple false statements and accusations” against him, his attorney Monique Pressley said in a statement.

The allegations of rape and sex assault were part of “an effort to cause damage to Mr Cosby’s reputation and to extract financial gains” from him, the attorney said.

Ms Pressley added that the allegations had caused “significant and lasting discredit” to the actor’s reputation.

The seven women named in the suit were Tamara Green, Therese Serignese, Linda Traitz, Louisa Moritz, Barbara Bowman, Joan Tarshis and Angela Leslie, Ms Pressley said.

Cosby’s countersuit to the lawsuits – first filed in December 2014 and charging him with libel, assault and slander – seeks unspecified financial damages.

The suits contend that Cosby slandered his alleged victims by calling them liars when they publicly accused him of sexual assault.

“Bill Cosby appears to be going to war against women who have sued him in Massachusetts and who allege that he has victimised them,” attorney Gloria Allred said.

“Such a tactic will not deter courageous women from fighting the battle against him.”