A Bradford paedophile was today exposed as a key player in a worldwide internet ring trading in horrific images of child abuse.

Mark Seel, pictured, was arrested as part of an international police operation against the Shadowz Brotherhood, a network of perverts who swapped paedophile material featuring babies and children.

Hardened officers described the images as among the worst ever encountered and said the Brotherhood even gave advice on how to 'groom' children for abuse using internet chat rooms.

Some members actively assaulted children.

Hundreds of officers swooped on 50 addresses across Europe yesterday at the end of a ten-month investigation into the ring.

But 29-year-old Seel, formerly of Pasture Lane, Clayton, was picked up last December because detectives felt he posed too much of a risk to wait until the final operation.

Despite admitting downloading a staggering 4,000 indecent images, the former marketing assistant was only given a three-year community rehabilitation order at Bradford Crown Court in June. As he walked from court, Seel, who had already served four months on remand, thanked the judge, claiming it would allow him to 'get to grips' with his problem. He had told the court how he himself had been abused.

A spokesman for the High Tech Major Crime Unit, which led Operation Twins, said that 16 targets had been arrested before yesterday's raids after risk assessments were carried out.

"In their cases it was thought we couldn't wait any longer and had to take them out then and there," he said.

A well-placed police source confirmed that Seel was one of the 16 held early.

When detectives arrested Seel, it led them to another member in America who had uploaded images of a six-year-old girl being abused.

The operation covered Germany, Holland, Belgium, Spain and Italy. It was backed by Europol, the European police agency.

Detective Chief Superintendent Len Hynds, who heads the National High Tech Crime Unit, said: "Those visiting this website were given the option of joining like-minded people.

"The kind of material they were distributing was of the most horrific kind and the advice they were providing to members was extremely disturbing.

"They provided advice on grooming children for abuse using chat rooms and that is an extremely worrying development."

And he said: "Just when you think you have seen the worst something else comes along and it comes as a real shock to the system."

The site was run by a hierarchy of paedophiles who ran 'star rating' for members depending on how much material they contributed. To begin with, visitors could only access limited bulletin boards and chat rooms, but as they climbed the star ladder, they gained deeper access to protected sites containing the most sickening images.

When detectives raided Seel's home - where he lived a 'hermit-like existence' - they found 95 per cent of his computer's memory taken up with thousands of sick images. They described his as a 'significant fish in his world'.

After the case Seel told the Telegraph & Argus: "It is an easy thing to fall into when you have been the victim of abuse yourself. I am just glad the judge has given me the chance to rebuild my life and try to make up for what I have done wrong."

He added: "I will not stay around here. I have lost my friends, my career and my fiancee."