Reports of sexual violence to a Tasmanian support service increased 18 per cent over the past year, according to new figures.

Key points: The Sexual Assault Support Service received almost 570 incident reports last year

The Sexual Assault Support Service received almost 570 incident reports last year Tasmania Police only received 180 reports statewide

Tasmania Police only received 180 reports statewide Support workers say victims fear they won't be believed, or that people will find out

Almost 570 incidents of sexual violence were reported to the Sexual Assault Support Service (SASS) in Hobart last year — a 54 per cent increase in five years.

Those figures only reflect the south of the state, making Tasmania's total even higher.

But very few of those cases are reported to police, with only 180 sexual assaults reported statewide last year.

SASS chief executive officer Jill Maxwell said she was not surprised by the huge difference in the number victims coming to her service and those reporting to police.

"There's always been a big difference between reporting to police and the figures that we see coming to us as a support service," she said.

"It's just that over the past five years we've seen a significant increase in those coming to us — which is a good thing.

"I think it's a positive sign in terms of the reporting to us. I'd just like to see more confidence with survivors in terms of translating that into reporting to police."

So would police.

Inspector Philippa Burk said reporting sexual violence to police was more than just attempting to get justice — it was also about changing community attitudes.

"I would just encourage people to report to us. Obviously if they're not reporting to police, we're not aware of it and we don't know the issue out there," Inspector Burk said.

"We're not going to stop it and change behaviour and change attitudes unless they do feel confident to come forward and report and have the matter fully investigated ... with the ultimate result being the perpetrator being held to account and charged."

Non-reporting a widespread problem

Non-reporting of sexual violence is a problem nationwide.

Jill Maxwell said fear of the legal process was one reason victims did not contact law enforcement. ( ABC News )

According to the Australian Bureau of Statistics' 2017 report Personal Safety, Australia, nine out 10 female victims do not contact police.

Ms Maxwell said the reasons were many and complex.

"What we put that down to is lack of information to people around their choice in terms of reporting, even in terms of support services," she said.

"[It is also] fear of being disbelieved; fear of the legal process itself.

"And blame — we've still got a culture in our community where we instantly go to 'well why was she out? why was she dressed like that? why had she been drinking that much?' So fear of being blamed.

"And also fear of breach of confidentiality — living in small communities, that's a big one."

Fear of the legal process, including the prospect of having to face their abuser in court and being cross-examined, is also a major deterrent to many victims, according to SASS.

Ms Maxwell said the way victims were handled and supported through the process, including in the court room, had come a long way.

Inspector Burk agreed.

"If victims of sexual violence come and report it to police they will be treated with compassion, empathy, dignity and respect," she said.

"Also I would encourage them to perhaps bring a support person with them or bring a sexual assault support person with them if they don't feel they've got the confidence in themselves to come into a police station by themselves."

The State Government committed $26 million over three years for measures to prevent and respond to family and sexual violence in Tasmania.