A transatlantic operation has busted an international paedophile ring that included parents who traded images of their children over the Internet, US customs officials have said.
The investigation led to 45 children aged between two and 14 being removed from care.
Two British men have already been convicted as part of the operation, US customs said.
One man was jailed for life for abusing a young schoolgirl and then posting images of the crime on the Internet, and another man was sent to prison for having child pornography, they said.
The new incitement, filed in a California court, charges nine Americans and six people in Denmark, Switzerland and the Netherlands with being members of the ring.
They are accused of conspiring to sexually exploit children, sexual exploitation of children and receiving and distributing materials involving the sexual exploitation of minors.
Mr Robert Bonner, the US Customs Commissioner, said the charges "relate to using and sexually exploiting children, often their own children, and then ... the publication of photographs of the crime on the internet."
The indictment alleges that they referred to themselves as "the club" and traded messages across the Internet requesting photographs of specific sexual poses.
One man asked for an audiotape so he could hear a child crying while being spanked, the indictment alleges, and another posed naked with an underage girl.
Operation Hamlet began last November when Save the Children tipped off the Danish authorities after finding a picture of a child apparently being abused on the Internet.
Danish police later arrested a man accused of posting a picture of his nine-year-old daughter on the internet and found a web of paedophiles across the globe.
Mr Bonner said in one case the ring had exchanged children to be abused. "With the power of the Internet, what might have been an isolated crime became a global crime."
He added: "In this case the normal safe harbour for children, which is their own parents, became these children's chamber of horrors.
"Instead of protecting their children these parents exploited them in the worst possible way."