Police are searching for a man who allegedly sexually assaulted a woman repeatedly at Victoria's Rainbow Serpent Festival – the latest in a spate of similar attacks at Australian music festivals.

The 21-year-old woman was walking in a camping area of the Lexton festival on the afternoon of Australia Day when she began talking with an unknown man, police have been told.

When she said she was going to walk to the main festival area, the man grabbed her by the hair and throat. He then pushed her up against a van and sexually assaulted her, police said.

The woman escaped, but the man grabbed her again and sexually assaulted her twice more.

Police have released a digital image of a man they want to interview. (Victoria Police)

She pushed him away and he bit her twice on the upper arm.

The man then got into a hammock and the woman returned to her campsite, police said.

Investigators have described the offender as being aged between 28 and 29 years old with sandy brown hair, blue eyes and a "pointy" nose. He is about 165-170cm tall and was wearing a grey shirt at the time.

They have also released a computer-generated image of a man they wish to interview, and have appealed for any witnesses or festival-goers who were in the festival's south camp section on the afternoon of January 26 to come forward.

The allegations are the latest in a spate of reported assaults at music festivals both in Australia and overseas.

Last month, police received allegations of five sexual assaults at Falls Festival in Tasmania, which was held at the end of last year.

Local Detective Inspector Steve Burk took to Facebook to condemn the behaviour.

"It's quite clear that the general belief of a lot of young people is that being inappropriately touched by someone else is what happens in the moshpit," he wrote on the Tasmania Police page.

"My view is if you're not comfortable treating women like that in the middle of the mall you don't treat them like that in the middle of the moshpit either."

The allegations also prompted Falls Festival organisers to call on "boys and men" to show respect.

Laneway Festival organisers responded by launching an abuse hotline for their string of festivals later last month.

At least 26 women reported being assaulted at the Schlossgrabenfest music festival in Germany in May 2016.