The BBC's Alison Holt: "It's taken hours of painstaking work"

Officers on three continents arrested 100 suspects after investigations in Britain and the USA produced a major breakthrough in the fight against Internet paedophilia.

Officers leading the operation, code-named "Cathedral", seized around 100,000 images, including pictures of children as young as two-years-old.

Packham: "Our priority is to find the children"

Those working on the case had become personally distressed by the appalling nature of the material they had collected in the massive operation to crack the ring known as the "Wonderland Club".

Police said their priority now was to track down the victims of the ring.

100,000 images: Children as young as two abused

In the UK, police raided 15 addresses in eight areas while colleagues in Germany targeted 18 people in seven states, seizing computers, video tapes and CD Roms.

Officers working in the US had arrested 32 suspects and it is also believed that they have been able to disable key servers used to store the illegal material for the network.

Other raids, all carried out at 0400 GMT, took place in Australia, Austria, Belgium, Finland, France, Italy, Norway, Portugal and Sweden.

The total amount of material seized is believed to be 10 times more than that taken in previous raids, officers said.

BBC Internet Correspondent Chris Nuttall: "These people are very difficult to track down"

Detective Superintendant John Stewardson, who led the operation from the UK, said: "I am confident this operation has targeted the hard core of individuals engaged upon Internet paedophile activity around the world".

Bob Packham, deputy director general of the UK's National Crime Squad, said Operation Cathedral had opened a new chapter in policing the Internet.

He said he believed that no other operation had ever brought together so many law enforcement agencies.

"Through this investigation we have recovered well in excess of 100,000 indecent images of children," he said.

"It has been a difficult and distressing investigation and I hope that our actions have prevented further abuse of children across the world."

'Horrendous legacy'

The operation began when officers with Sussex police, south-east England, received a tip-off from US Customs officers which led them to the "Wonderland Club" network.

Stewardson: "To join Wonderland Club you needed 10,000 images"

Aided by the National Criminal Intelligence Service, they drew in Interpol and police forces across Europe when it emerged that there was almost constant international contact over the Internet between members of the ring.

Initial investigations led all the police forces to meet during the summer at Interpol's Paris headquarters.

Det Supt Stewardson said the "Wonderland Club" paedophiles had left a "horrendous legacy" of abuse among their victims.

"There are people who simply exchanged material and some who produced it," he said.

"We have got one producer in the UK who was part of this group.

"The children abused were of both sexes and some it would appear were as young as two, although we don't know who these children are yet.

"The content would turn the stomach of any right-minded person."