The Interpol-led probe involving 170 countries was launched after a hacker posted 99 child porn images on a European website, which attracted 12 million hits in just 76 hours.

More than 2,800 computer Internet protocol (IP) addresses were traced back to Australia and federal police identified all of them in a six-month operation, Police Commissioner Mick Keelty said.

"You will see more arrests, the investigations are continuing," Keelty told reporters. Keelty said the first arrests were made in cases where children might be in danger and four children had been taken from their homes.

Several teachers, a federal police officer and a sports administrator were reportedly among those arrested.

"It's really one of the largest single operations we've done on child pornography with our international partners and our state police partners here in Australia," Keelty said.

"You're talking about 12 million hits from around the world but in a small time period of three days.

"In Australia the operation has netted over a million images of children, and these are not children in passive positions, these are children who are being abused."