Police arrested 30 people in a series of arrests across Britain on Monday morning as part of a crackdown into Internet child pornography.
Those detained are suspected of paying for access to US-based servers that allowed them to download images of children being sexually abused. Some of the pictures involved children as young as five, police said.
The operation, code-named "Ore", was coordinated by the National Criminal Intelligence Service (NCIS). Officers are understood to have worked closely with authorities in the US, who gave UK police details of those who had accessed the servers.
The NCIS said in a statement that this was the first time that they had successfully targeted people suspected of using the Internet to buy images of children being sexually abused.
"This is an excellent example of all the UK policing agencies coming together in a coordinated way to tackle a relatively new and growing problem," said detective superintendent Peter Spindler in a statement. "We will continue these operations to protect children and show paedophiles that law enforcement agencies will find them regardless of which area of the Internet they use," he added.
Operation Ore is the latest in a series of coordinated raids against suspected Internet paedophiles. Fourteen people were arrested in Britain last October, and a total of 100 were detained in an operation in America in August 2001.