Image copyright NAtional Crime Agency Image caption Clockwise from top left: John Denham, Matthew Stansfield, Adam Toms, Matthew Lisk, Robin Hollyson, Christopher Knight and David Harsley

Seven men described by detectives as "monsters in disguise" have been found guilty of a string of serious sexual offences against children.

They were part of an "organised paedophile network" with "tentacles around the world" that arranged the rape of young children, some of them babies.

Three young victims - a baby, a toddler and a child under five - have been identified from thousands of images seized as part of the inquiry, but police believe there are more.

The National Crime Agency (NCA) said the offences were "as vile and depraved" as it had ever come across.

Detectives said the group were "incredibly skilled" at grooming victims, families and each other in order to find children to prey upon, and went to great lengths to plan the abuse without being caught.

'Monsters in disguise'

One member even developed a relationship with a pregnant woman "with the sole intention" of abusing her baby after its birth.

The gang was "more than happy" to drive for three to four hours across the UK, spend less than half an hour with a victim, and then return to their jobs.

The NCA's Deputy Director of Investigations Graham Gardner said "on the face of it", the men operated as individuals in communities where no-one would suspect them.

But they were, he said, "monsters in disguise."

"They have groomed women who were pregnant, they've groomed families and people who can get them access to children," he said.

"Only when they come together and commit these horrific crimes does it become very apparent what their endeavours were."

Image caption Graham Gardner from the NCA, described the men as "monsters in disguise."

The men first contacted each other and openly discussed their intentions on adult sex websites, social media and online conferencing sites - there is no evidence they used the so-called anonymous "dark" web.

Senior investigating officer at the NCA, Adam Robinson, said: "They were all promiscuous and all involved in online sex forums for their own gratification

"They used terms like 'paedo' - that's how they introduced each other."

Mr Robinson said one of the men described himself as a "nepiophile", meaning someone sexually attracted to children under two.

'Smaller the better'

On one chat log uncovered by detectives, two of the offenders discussed their preferences.

When asked: "How small you like mate?", the other replied [the] "smaller the better buddy."

As well as carrying out abuse themselves, the men also arranged to meet to view live images of sexual abuse streamed over the internet from abroad.

Mr Robinson said the images that he and his colleagues viewed were "horrendous" and some needed to have breaks from work because the material was so distressing.

Image copyright Thinkstock Image caption The material was traded on the open internet rather than the "dark web"

"It was the most disgusting material you've ever read or seen," he said.

Those who could get access to victims were granted "elevated" status within the network.

Officers said online conversations between the men also contained references to using drugs against victims - both controlled substances and over-the-counter medicines.

They openly discussed what dosages were needed to induce a particular state in a child of a certain age.

The NCA was called in last September when one of the men, Adam Toms, approached Avon and Somerset Police.

Two men had previously been arrested as part of separate inquiries by other police forces, and it is thought Toms, 33, felt the net was closing in.

He admitted various offences and the investigation, codenamed Operation Voicer, was launched when the NCA discovered Toms and the other suspects were part of a UK-wide network with global links.

'Previous convictions'

As well as the NCA, the inquiry has involved four police forces - Avon and Somerset, Bedfordshire, Humberside and Wiltshire, nine local authority child protection teams, the Crown Prosecution Service, the EU law enforcement agency Europol and child abuse investigation teams across the UK.

In total 11 people have been arrested, four of whom are on police bail.

Material which could lead to the arrest of other paedophiles has been sent to police abroad, via Europol, to north America, South America, Scandinavia, Australia and Africa.

Seventeen "packages" of material have also been sent to police in UK forces for them to pursue their own investigations.

The seven men are all said to be in work, but not in occupations that allowed them unsupervised access to children. One of them is a father.

Three of them - Robyn Harsley, David Hollyson, and Matthew Stansfield - had previous convictions for accessing child abuse images and were registered sex offenders.

Stansfield and John Denham were found guilty after a trial at Bristol Crown Court which ended on Wednesday; five other members had earlier admitted various offences.

All the men are due to be sentenced at a later date.

Protection and safeguarding measures have been put in place for the three known victims, together with 21 other children who were thought to be at risk.