This was the most sophisticated and organised group in existence

Detective Superintendent Peter Spindler

Membership of the club was by invite only and on the "payment" of 10,000 indecent pictures of children, which were then encrypted and swapped on the internet.

During raids in 1998, codenamed Operation Cathedral, police seized 750,000 images of children.

Eight men in the UK were charged with conspiracy to distribute pornographic images.

One, unemployed 40-year-old Steven Ellis, killed himself shortly after his arrest; the rest admitted the charges.

Hardcore

Police, horrified by what they uncovered, believe the men are the hardcore of paedophiles using the internet to swap images of children being sexually exploited.

The eight arrested

Ahmed Ali, 30, a taxi driver from Tulse Hill, south London Ian Baldock, 31, a computer consultant from St Leonards, East Sussex Andrew Barlow, 25, unemployed, of Bletchley in Milton Keynes Gavin Seagers, 29, a computer consultant from Dartford, Kent Antoni Skinner, 36, a computer consultant from Cheltenham Frederick Stephens, 46, a taxi driver from Hayes, Middlesex David Hines, 30, unemployed, from Bognor Regis in West Sussex Steven Ellis, 40, unemployed, from Norwich

Detective Superintendent Peter Spindler, of the National Crime Squad, said the convictions marked the end of the British part of the operation.

"We have taken out those who considered themselves the best and we retrieved three quarters of a million paedophilic images from their computers," he said.

"I won't be complacent and say there aren't others out there but this was the most sophisticated and organised group that was in existence."

The images discovered in the raids that finally broke the ring included photographs of naked boys and girls, aged from infancy to puberty. One was a baby less than a year old.

Police in Britain, the United States and countries across Europe had difficulty cracking the network, which used encryption technology to distribute the images.

Police, charities and social service workers are still trying to trace the children featured in the images.

Gavin Seagers was the last to plead guilty

They hope that finding the children will enable them to bring specific charges of abuse rather than the lesser charge of conspiracy.

Twelve men in the UK were originally arrested during Operation Cathedral.

David Chaiken, a computer consultant from Maidenhead, Berkshire, was charged separately with possession and distribution of indecent images of children.

He was sentenced to eight months imprisonment for distribution and three months concurrent for possession in June 1999, and was placed on the sex offenders register for 10 years.

The NCS did not proceed with cases against three other men arrested.

The seven convicted men, who will be sentenced next month, face the maximum sentence for conspiracy to distribute internet porn - three years in jail.

Future offenders are warned the penalty will rise to 10 years when the Criminal Justice and Court Services Bill goes through parliament later this year.