A 13-year-old boy yesterday became the youngest person ever to be convicted of dealing in child porn - for possessing more than 300 paedophilic images on his home computer.

The teenager, who cannot be named for legal reasons, was given an 18-month supervision order on condition he attends a rehabilitation course.

He admitted nine charges of possessing indecent images of children.

A total of 326 images displaying young children engaged in sexual acts and bestiality, as well as half a dozen images involving a young baby, were found on the hard drive of the boy's computer.

District Judge James Prowse, sitting at Teesside Youth Court, said that the boy, from Thornaby, Stockton, had become an "unwitting victim" in an Internet ring peddling child pornography.

The teenager, who appeared in court wearing black trousers and a black jumper, spoke only to confirm his name, address and to accept his sentence.

The court heard that he had initially logged on to an Internet chatroom in search of teenage girls of a similar age.

He soon became embroiled in a sordid trade of pornographic images after logging on using an obscene pseudonym.

Officers from Greater Manchester Police monitored the chatroom as part of a four-month national operation codenamed Operation Appal, which has led to more than 30 arrests nationwide.

Cleveland Police officers raided the young boy's home expecting to find an adult paedophile, the court heard, and were surprised to find that the child was involved.

Mr Prowse said: "You are in an unusual position and this is an unusual and disturbing case.

"It is an unusual case because of your age. The courts much more usually find they deal with adult individuals who have an unhealthy interest in these images.

"It is a disturbing case in that someone as young as you was so readily able to get access to this type of material, not just photos of girls of young age, but children engaging in thoroughly indecent acts.

"You yourself became an unwitting victim of the pornography that is available on the Internet to be peddled."

Mr Prowse accepted evidence that the teenager had downloaded large batches of images without knowing the exact content in his efforts to find pictures of girls his age.

He said that the boy would not necessarily have chosen all the pictures he actually downloaded had the choice been available.

He ordered the hard drive on the boy's computer be destroyed, but allowed the rest of the equipment to be returned to the family.

The youngster has signed on the sex offender's register with Cleveland Police and will take part in a rehabilitation course.

The judge ordered that £83 prosecution costs be paid within 28 days.

He declined the opportunity to place a binding order on the parents, saying: "All the indications are you are being well brought up in a secure family environment."

Later, a spokesman for Cleveland Police said the 13-year-old was the youngest person in the force area to be placed on the sex offender's register.