AUTHORITIES in the US, acting on a lead from Australian police, charged 60 people with being part of a global network of child pornographers.

US Attorney-General Michael Mukasey said the far-reaching case began with a single lead from Australian police in what became known as Operation Koala in Europe and Operation Joint Hammer in the US.

"From that initial horrible discovery, the investigation grew to reveal connections in nearly 30 countries around the world," Mr Mukasey said.

By scouring the suspects' email accounts and computers, authorities in Europe, Canada, and the US have been making further arrests for more than two years.

Last week, US authorities charged a man in California with inducing an 11-year-old girl to engage in sexual conduct and with creating molestation images to distribute.

Authorities said the investigations were continuing as individuals in one child pornography network led to other such networks. The US arm of the investigation has also led to the identification of 11 child victims.