The 43-year-old woman is reportedly a witness to an incident at a music studio in London in the early 1990s, the Australian reported.
The woman told Channel Seven she had not contacted police earlier because she thought they would not believe her.
It is understood Rolf Harris denies any wrongdoing
Harris was named in April as the TV entertainer arrested by police investigating allegations of sexual abuse in the wake of the Jimmy Savile scandal.
The 83-year-old was first interviewed under caution on November 29 after attending a south London police premises by appointment.
He was then arrested on March 28, two days before his 83rd birthday.
Scotland Yard said: "An 82-year-old man from Berkshire was arrested by officers on Operation Yewtree on suspicion of sexual offences. He has been bailed to a date in May pending further enquiries. The individual falls under the strand of the investigation we have termed "others"."
It is understood Harris denies any wrongdoing.
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