A 33-year-old paedophile who stockpiled more than 3.5 million indecent images of children - believed to be the largest amount ever uncovered in this country - was put behind bars for seven years today.

Thomas Owen had also paid a family in the Phillipines almost £1,000 for their seven-year-old son to be abused and filmed for his personal sexual gratification and distributed other images with fellow perverts.

Liverpool Crown Court heard that Owen had a preference for images of young boys and had meticulously filed photographs and movies by category and genres on hard drives and a laptop computer.

There were so many images that police had to abandon the task of putting them into categories after counting more than half a million.

After sentencing bearded Owen, Judge Brian Lewis said he represented a significant risk of serious harm of committing more offences and extended his licence by three years.

He said that over seven months in 2011 he paid the Filipino family, or an agent, a total of £863 for three pornographic images of the boy.

"It is, of course, the case, repeatedly the case that poor Filipino families are deliberately targeted by the sort of depraved exploitation you embarked upon.

"In their desperation and their poverty they were effectively prostituting their children for people you in the West to satisfy your salacious and perverted sexual appetites."

He said that the boy is now nine but the three images of him were "the tip of the iceberg" as Owen had more than three million indecent images of children.

Judge Lewis said that the court "sadly" had to deal with many cases involving the exploitation of children for sexual purposes, "but rarely I can say has one come across a case with such exceptional levels of criminal activity as this one."

He pointed out that Owen had been jailed for three years in America in 2003 for indecency with an eight-year-old boy at Camp America, where Owen was a volunteer worker, which showed his interest was "not simply at arms length in terms of photographs and images" and that on one occasion at least he had been prepared to actually abuse a child.

"No-one should be under any misapprehension that these images that you were holding on your computer represent hundreds of thousands of victims because that is what these children were.

"A lot of them were possibly unconscious of the fact at the time but so often the courts see people whose lives have been scarred for decades because of this sort of exposure in their childhood and that is the damage it does."

Owen who pleaded guilty to three charges of causing or inciting the Filipino boy to became involved in pornography, four of distributing indecent images, 18 of making indecent images and two of making and possessing them with a view to distribution.

The judge ordered him to sign the Sexual Offenders Register for life and imposed an indefinite Sexual Offences Prevention Order.

Chris Hopkins, prosecuting, had told how Owen's perverted behaviour was uncovered when police arrested a known sex offender in Northampton connected with indecent images of children on an on-line file sharing site.

It was found that he had been chatting on line with an internet user about abusing children and this was identified as Owen.

Police officers went to his home in Wilton Street, Wallasey, and a seized his hard drives and laptop and an initial examination revealed indecent images of young boys.

The equipment had been encrypted using sophisticated software but when questioned, Owen gave officers the necessary passwords and codes and admitted downloading indecent images.

Examination showed he had spoken on line with two men about purchasing images of a young Filipino boy from a couple and computer logs showed he had also distributed indecent videos of child abuse.

As well as 489,491 indecent photographs, of which 60,000 were in the two most serious categories, there were more than three million others which were not analysed.

There were also 14,190 indecent videos, 9,000 in the two most serious groups, and a further 29,000 videos which were not examined.

When interviewed, Owen was frank and admitted he had conversations with a man called Art in the Phllipines over the internet telling him what scenes he wanted the boy photographed in. "He said he had a preference for children in nappies and swimwear."

He agreed "that he had been sponsoring the family by his payments." Further questioned he said he preferred images in the least serious category and would swop images in more severe categories for them.

Owen has no previous convictions in this country but had the conviction in South Carolina for abusing a boy and as well as his three-year-old jail term had a further seven years suspended and was deported after his release.

Zillah Williams, defending, said that Owen had helped police with the passwords and codes to unlock the encryption methods he had used. "He was shocked and surprised at the numbers talked about but does not seek to challenge them."

She said that he had had a difficult upbringing and had sought out psychiatric help and would take advantage of help available in prison and after his release.

After the hearing Detective Chief Inspector Steve Fell from Merseyside Police's force crime operations unit, said: "Today's sentence should send out a clear and stark message to paedophiles who think they can hide behind the anonymity of the Internet to commit horrific crimes against innocent children - you can and will be caught.

"Thomas Owen had more than 3.5 million indecent images and videos of children on his computers - the most we, as a police force, have ever seen. Many thousands of them were the most serious child abuse imagery there can be.

"Every single one of those images represents the horrific, shameful and degrading sexual abuse suffered by real children at the hands of paedophiles.

"Merseyside Police has specialist officers working tirelessly with other agencies to identify these children, no matter where in the world they live.

"I am certain that all will have suffered greatly because of sexual predators like Thomas Owen and all will sadly become repeat victims each and every time their image is viewed online.

"A massive amount of work is done by law enforcement agencies throughout the world to identify paedophiles like Thomas Owen, infiltrate their networks and uncover the evidence we need to put them behind bars.

"During this investigation Merseyside Police worked with other UK forces and CEOP (the child exploitation online protection centre), as well as agencies in other countries who share our desire and determination to protect children from depraved and dangerous men like him."

"We will use every tactic and technological advancement available to ensure people like him cannot and do not get away with the terrible crimes they have committed. Their young victims deserve to see justice done."