More teenagers are posting sexual images of themselves on the internet and stripping naked in front of webcams, an international expert has said.

Dr Ethel Quayle, of Ireland, a consultant with the research organisation Copine (Combating Paedophile Information Networks in Europe), has been in New Zealand speaking about the “astronomically large” increase in internet child pornography.

Young people posting self-produced material on the internet was an increasing concern, she said.

“There are some people who don’t try to seek to meet children but try to encourage them in online sexual behaviour. Webcams become tools of getting children to undress online. It’s all about breaking down a child’s defences, making the child feel they have to comply.”

New Zealand’s Netsafe executive director Martin Cocker said the group knew of a handful of cases where New Zealand children had stripped naked in front of webcams and uploaded self-generated sexual images of themselves.

“A lot are doing it without being groomed, they’ve done it because their mates have put them up to it … but they don’t realise the gravity of it.”

Education was the best way to protect children, he said.

Dr Quayle said United States research suggested that many young people were aware of internet grooming.

“They knew that they were talking to adults online, and that the adult probably wanted a relationship with them and it might be sexual. They are, however, naive in thinking that the person might think that they are really special and that they were offering them love …”

While self-generated material was increasing, more offenders were downloading, exchanging and producing pornographic images of children being abused, she said.

“The whole issue of victimisation is still a huge problem. Very few children are identified. It’s difficult to locate children in terms of geographic locality.”

Internet watchdogs and authorities were only seeing the tip of the iceberg in the actual volume of material and numbers downloading pornographic images of children, Dr Quayle said.