Key Points:

A new international survey has found one in four New Zealand girls is sexually abused before the age of 15, the highest rate of any country examined.

The results show, for the first time, that Maori girls suffer roughly twice as much sexual abuse as European girls - 30.5 per cent of Maori compared with 17 per cent of Europeans in Auckland, and 35.1 per cent of Maori compared with 20.7 per cent of Europeans in the northern Waikato.

The survey, based on a World Health Organisation study that asked the same question in 10 developing countries and Japan, prompted sexual abuse counsellors yesterday to alert parents to the signs their children may be suffering unwanted sexual contact.

Nearly 3000 women were questioned about unwanted sexual contact before they were 15.

Hamilton Abuse Intervention Project co-ordinator Lila Jones said the "horrific" figures were no surprise.

"It's sadly quite rife amongst our young people," she said. "Our young people are divulging sexual abuse, particularly within the family and Mum's new partner or previous partner, but sometimes Dad has been the culprit and/or his mates."

Child, Youth and Family Minister Ruth Dyson said the sexual abuse of women and children "cannot be tolerated in a civilised society and we must act collectively and collaboratively to remove this behaviour from our homes and our lives."

She said the Government was committed to working with non-government organisations to address abuse.

Auckland Sexual Abuse Help clinical manager Kathryn McPhillips said the figures showed the need for parents to "get informed about what to look for" in their children.

"The signs are not necessarily anything other than the child being upset - withdrawing, regressing to some earlier behaviour, becoming more aggressive, not eating, eating more, going back to bedwetting. Sometimes overt sexual behaviour with another child or a sexually transmitted disease, but that's not likely."

The 2855 randomly selected women aged 18 to 64 in Auckland and northern Waikato were asked: "Before the age of 15, do you remember if anyone in your family ever touched you sexually, or made you do something sexual that you didn't want to do?"

After answering the question about their family, they were asked: "How about someone at school? How about a friend or neighbour? Has anyone else done this to you?"

Overall, the survey found that 23.5 per cent of women in Auckland and 28.2 per cent in the Waikato had experienced such abuse.

The median age when the abuse started was 9 and the median age of perpetrators was 30. Half the women said the abuse happened once or twice, a quarter said a few times and a quarter many times.

For 83 per cent of women, there was only one perpetrator. For 14 per cent there were two, and for 3 per cent more than two.

Uncles were the most common male perpetrators (24 per cent), followed by brothers/stepbrothers (14), fathers (13), cousins (11), stepfathers and grandfathers ( 9), other family members (5), family friends and acquaintances (14) and strangers (1).

More than half (54 per cent) of those who suffered childhood sexual abuse later suffered sexual or physical violence from a partner, compared with 31 per cent of other women.

Lead author Dr Janet Fanslow of Auckland University said the questions were clearly answered in different cultural contexts in different countries. For example, the lowest rate of childhood sexual abuse (1 per cent) was in rural Bangladesh, where girls often married as young as 9.

Auckland Rape Prevention Education director Dr Kim McGregor warned the survey covered only women so it did not necessarily mean that Maori men were also more likely to be perpetrators.