Police yesterday welcomed a ten-year prison sentence imposed on an auxiliary nurse who sexually abused children and posted images and videos of his crimes on the internet.

Paul Stephen John, from Leominster, Herefordshire, pleaded guilty to 50 offences, including child cruelty and sexual assault as well as the creation, distribution and possession of indecent images of children.

Sentencing John at Worcester Crown Court, Judge John Cavell told the 33-year-old it had been one of the most horrific cases he had heard of for many years.

The judge accused him of "sadistic and perverted conduct at its very worst".

West Mercia Police first investigated the defendant after a local school reported seeing bruises on a young child. Thumbnail images of children being abused were found on his computer and an investigation was launched which involved social services and the Hi-Tech Crime Unit at West Midlands Police.

Officers unearthed more than 4,300 indecent images during their inquiries, many of which had been distributed to offenders worldwide.

John used encryption software to prevent police accessing the files but gave officers the password when unencrypted files he had sent to another offender in Kent were recovered. The offences were all committed between 2000 and 2004.

At his sentencing last week, Judge Cavell also made an order that John be placed on the Sex Offenders Register for life and banned from having any contact with children following his release.

The judge said the public owed investigating officers who had brought the case "a debt of gratitude".

Acting Detective Inspector Callie Bradley said the sentences should serve as a warning to other offenders.

The officer who led the investigation said: "This investigation involved a great deal of work, not only by officers from Herefordshire, but also by partner agencies such as social services and the West Midlands Hi-Tech Crime Unit.

"This case shows our continuing determination to bring to justice all those individuals who seek to abuse children and we are pleased that the judge publicly recognised this."

A female co-defendant, who cannot be named for legal reasons, was given a 30-month jail sentence after she pleaded guilty to child cruelty.

She was also found guilty of taking indecent photographs of children during a trial last year but cleared of any sexual activity with them.

Judge Cavell said the woman's guilty plea proved she knew what was going on and yet had done nothing to protect the children.