Less than a third of sexual violence cases reported to the police make it court, according to a new report released by the Ministry of Justice.

Photo: RNZ / Sarah Robson

Out of the almost 24,000 cases of sexual violence reports made to police between July 2014 and June last year, just 11 percent resulted in a conviction.

The government and advocacy groups say progress is being made, but a lot more work needs to be done.

Findings from the report:

Of the sexual violence victimisations reported to police, more than three-quarters (77 percent) occurred when the victim was aged 24 years or less

For 63 percent the victim was a child or young person aged 17 years or younger

Females experienced 87 percent of the reported victimisations and males 13 percent

37 percent had police action taken against a perpetrator

11 percent resulted in a conviction

6 percent had a prison sentence.

56 percent of reported victimisations had an investigation undertaken but Police were unable to proceed against a perpetrator at that time

The under-secretary to the Minister of Justice, Jan Logie said the report did not make for happy reading, but it was crucial to have good data to measure progress.

"The best we've had until this point was a 2009 Ministry for Women research, that only looked at adult cases and case files, this is a really significant point for us to finally as a country take responsibility," she said.

Ms Logie said one slither of hope in the report was that just in the last year police saw a 34 percent increase in the number of investigations resulting in court action.

The government will be introducing legislation into Parliament this year to address some of the barriers victims face.

Kathryn McPhillips, from Auckland sexual abuse support organisation HELP, said she would like to see changes to the court process for children.

"Children are put into situations as if they're small adults, and while the legislative changes are going to address that to some degree in terms of ensuring children can understand the questions put to them, it still seems that our processes are fixated on criminal justice rather than getting children safe," she said.

The report stated it was estimated that less than 10 percent of sexual violence was reported to police.

But the statistics were not surprising to Sexual Abuse Prevention network chief executive Fiona McNamara.

"The low likelihood of a conviction is one of the reasons why people are unlikely to report," Ms McNamara said.

"The process is such a huge experience for people to go through, so many people will wonder why they put themselves through something like that if it is really unlikely to result in a conviction," she said.

But she said she was thankful there was a lot of work already being done to improve the system.

"Some of which is highlighted in this report, like changes so that evidence that is given at a trial can be reported, so that a survivor doesn't have to repeat it at any retrial, it can just be replayed," Ms McNamara said.

"There is also a lot of work being done at the moment to educate those who play a key part in the system such as court staff, or judges and police."

Police adult sexual assault manager and detective inspector David Kirby said that was in part due to implementation of the Solicitor General's guidelines for prosecuting sexual violence.

"There has also been an increase emphasis in the training around empathy and supporting the victims through the whole process," Mr Kirby said.

"We now have national ASA specialised investigators pretty much in every major city,' he said.

Mr Kirby said police could still do more, so they were seeking feedback from victims on their website.