An investigation has been launched at a young offenders unit in Wolverhampton after confidential information about inmates was handed over to a visitor.

Up to 20 sheets of paper containing the names, ages, offences, wing and sentence of about 230 inmates at Brinsford Young Offenders Institution in Featherstone was given to the brother of an inmate.

Reece Chisholm, of Hall Green, Birmingham, received the information when he visited 18-year-old brother Luke Kennedy at Brinsford on May 6.

The Prison Service has since launched an investigation over the security breach and said it takes such matters “very seriously”.

Mr Chisholm, who is unemployed, said he was concerned how easily he got hold of prisoners’ details, which included those of his brother who is serving time for assault. He said it happened when the prison was returning his own identification in which they included the documents.

Mr Chisholm, who has himself been in prison five times, twice in Brinsford, said: “I’m the oldest so I take care of him.

“I try to go and see him as often as I can, once every week.”

He said Mr Kennedy had lived with him since his mother Claire Kennedy, strangled his half-sister Courtney Mulroy, aged six, with a skipping rope.

She admitted manslaughter on the grounds of diminished responsibility in 2007 and was imprisoned for a minimum of three years.

He added the lapse could have made the inmates vulnerable to attack if the wrong person had got hold of details about their backgrounds.

“These kids have done something wrong but some of them might be trying to turn their lives around,” he said.

“This could have fallen into the hands of someone else who could have been waiting for them to get out.

“It’s a joke and disgusting how they can give away people’s information like that. I’m surprised how easily it happened, it’s just pathetic.”

Mr Chisholm, aged 21, gave the papers to his solicitor, Regan Peggs of Williamson and Soden, who handed them to the police. A Prison Service spokeswoman said: “We take the security of information very seriously. We are investigating this issue as a matter of urgency.”

They refused to confirm what information had been released.

Head of policy at the Prison Reform Trust Imran Hussain criticised the leak and said the prison needed to tighten its security.

He said: “Clearly something’s gone wrong. This kind of information is confidential and very personal and I think everyone would expect the Prison Service to keep a close eye on it.

“The prison needs to look at its procedures to make sure this kind of breach doesn’t happen again. It has a duty to look after information properly.”