An online pornography ring targeting thousands of Australian schoolgirls has re-emerged after police had closed it down earlier this month.

On the foreign-hosted forum, users post requests for people to share pornographic images of girls at schools or universities in exchange for other images.

The page reportedly features naked photos of teenage girls, some with their names, so others can rate them.

Police said the original pornographic site involved a number of images of girls from at least 70 high schools from across the country.

Cyber law expert from the University of New South Wales David Vaile said the international nature of the pornography ring should be of great concern to authorities.

"When you're starting to get organised some international efforts to pursue this then that's the sort of thing that should be ringing alarm bells in police and law enforcement agencies," he told the ABC's AM program.

'I feel violated and upset'

In a statement, the Office of the Children's E-Safety Commissioner said it was in contact with a number of those involved in the complex supply chain for the website.

Natalie, who wishes not to use her real name, is a victim of the site.

She had intimate photos taken by a professional photographer when she was 17 years old.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Listen Duration: 3 minutes 9 seconds 3 m 9 s Listen to Michael Edward's story Download 5.8 MB

In a written statement to AM, Natalie said the photographer later posted the photos to the site.

"I found out about it when random people and friends that had been told about it, began messaging me and calling me to tell me," she wrote.

She said she contacted the photographer and asked him to take the photos down, but he refused.

Natalie then contacted the police, but said nothing happened.

"I feel violated and upset," she wrote. "Especially that people would save the photos and use them against me and re-post them.

"How would you feel if that was your daughter, mother, sister or wife being violated in such a way?"

Revenge porn site difficult to keep track of

Writer Amy Gray who researches revenge porn said she had seen at least four other site similar to this one.

"It's showing them that they can use previously trusted photos. To try and shame and upset them and hurt their reputation," she said.

Laws do exist for those who engage in 'revenge porn' but legal experts said it was often difficult for law enforcement to keep track of online sites, especially when they are hosted overseas.

"Sometimes they [the men] will specify what type of shots they want to see, and sometimes they will say 'I have got these types of shots I can offer as trade'," Ms Gray said.