Victims of sexual attacks are reluctant to come forward and report crimes because so few end in conviction, laywers and experts say.

One of the biggest hurdles in prosecuting rapes are that they regularly happen behind closed doors and have no witnesses, according to the Victorian Centres Against Sexual Assault. As a result, there are problems meeting the burden of proof.

Sexual attack ... 'These sorts of incidents nearly always take place in private, and it is very difficult to prove.' Credit:iStock

"These sorts of incidents nearly always take place in private, especially if there are multiple offenders, and it is very difficult to prove," the centres' spokeswoman, Carolyn Worth, said.

"Less than 2 per cent of sexual crime cases go through to a successful hearing ... it's incredibly low, and rape has a lower conviction rate than any other crime."