(CNN) Interpol has saved 50 children and prosecuted nine sex offenders after uncovering an international pedophile ring that was sharing child abuse images on the dark web.

Police believe there are still 100 children who have not yet been located, Interpol said in a press release Thursday, adding that it expected to make more arrests and rescues.

Offenders have already been prosecuted in Thailand, Australia and the United States, Interpol said, and police in nearly 60 countries are involved in the investigation.

In the report, Interpol said it launched "Operation Blackwrist" in 2017 after discovering material depicting the abuse of 11 boys all aged under 13 on the dark web , a part of the internet that cannot be found by mainstream search engines. The images were on a subscription-based website that published new images weekly to almost 63,000 users worldwide.

In June 2017, Thailand's Department of Special Investigations (DSI) took on the case, working closely with Interpol's Liaison Bureau in Bangkok and investigators around the world including in the United States, Bulgaria, New Zealand and Australia.

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