So far 22 people have been arrested including two UK men

The children were identified from thousands of images seized in an international operation involving the FBI and Queensland police in Australia.

The victims were traced to addresses in the UK, the Child Exploitation and Online Protection Centre (Ceop) said.

So far 22 people - including two men from the UK - have been arrested.

World-wide ring

Six other British men have already been jailed for their roles in trading and receiving pictures and videos on the network.

These images are crime scene photos where children are being subjected to sexual abuse - this is not 'child pornography' Paul Griffiths Ceop

Investigators successfully infiltrated the online newsgroup which also had members in the United States, Australia, Canada and Germany.

Paul Griffiths who heads the victim identification team at Ceop, said the children were subjected to horrendous abuse.

"In every image there is a child. These images are crime scene photos where children are being subjected to sexual abuse. This is not child pornography."

He said: "It's important to remember too though that these children were not missing.

"They were located in the place where they were supposed to be safe - their own home - where their abuse was recorded and made available over the internet to satisfy sickening sexual desires of a deviant group of individuals."

'Run like a business'

Some 400,000 images were seized during the two-year operation and some were passed to individual countries for investigation.

Officers in the UK used facial recognition software and painstaking detective work to identify victims from clues in each image.

It's definitely the largest and most sophisticated and disciplined group that we have ever seen operating in this environment Ross Barnett, Queensland police

Undercover Australian investigators discovered and infiltrated the ring in January 2006.

FBI executive assistant director Stephen Tidwell said the online gang was run like a business with indecent images used as a substitute for cash.

He said: "This is beyond a quantum exponential leap for us to see folks that have gone to this much trouble to produce this kind of volume of horrific exploitation of children."

Ross Barnett, detective chief superintendent with the Queensland Police Service, said sophisticated attempts were made to block police.