The actor has strenuously denied the allegation. 

It is understood the woman made the complaint against the actor to Shoalhaven police about a week ago.

Police media will not say where the woman is from or her age, or how old she was at the time of the alleged offence.

The star has “emphatically” denied the claim which allegedly happened on Sydney’s eastern beaches in the 1970s.

“Police are investigating an allegation of a historic sexual assault on Sydney’s eastern beaches,” a NSW Police spokeswoman said.

“The allegations were reported to police earlier this month and relate to a matter from the 1970s.”

Ignite Elite Artists, Jarratt’s representative, in a media statement said the 65-year-old “emphatically and completely denies the allegations of sexual assault”.

“These allegations are completely unfounded and untrue,” Ignite Elite Artists said.