The Rainsbrook Secure Training Centre in Onley, Northamptonshire, opens on Friday and is expected to house up to 40 children.

It is being run by Rebound ECD, the same Group 4 Security company that runs Britain's first child jail, the Medway Secure Training Centre in Kent.

Inside a cell at the Medway Secure Training Centre

In January, the Social Services Inspectorate published a damning report claiming staff used excessive force against children and were poorly trained.

It said the centre was "facing a crisis". It had seen 14 disturbances since it opened in April 1998 and more than a third of its staff had left following assaults.

Offenders, aged between 12 and 14, felt a sense of "injustice and powerlessness".

A report by the Howard League charity says it is "a huge mistake" to open a second jail.

It is against the incarceration of young children and says it is not an effective way of treating them.

'Criminal attitudes strengthened'

Assistant director Fran Russell said: "Experience has already shown that this kind of institution strengthens the criminal attitudes of the children it is supposed to help.

"The cost of this mistake is not just the money it takes to build and run secure training centres, but also the wider cost to the community of exacerbating a child's offending in the long term."

The Howard League says a similar institution in Northern Ireland, the Lisnevin Training Centre, was found in 1995 to have a re-offending rate of 100% within two years.

But it says an intensive community supervision project in Sheffield was forced to close last month due to lack of funds.

This is despite it costing �10,000 a year to run, compared to an estimated �110,000 a year for the child prisons.

The Howard League claims that, in its three years, it has managed to reduce re-offending rates by 60%.

''Out of control'

Fran Russell believes the introduction of child prisons was a result of several factors, including the killing of Jamie Bulger in Liverpool, a number of council estate disturbances in 1995 and media highlighting of cases of serious repeat offenders.

"This gave the impression that young people were out of control when there are very few children who are persistent offenders and repeat offending only tends to last for a short period," she said.

Rebound says it has made improvements at Medway and assault rates on staff have fallen.

It says that there is also more support for young people and greater confidence among staff.

But the Howard League argues that the concept of jailing children is "fundamentally flawed".