Government plans to give courts the power to lock up 10-year-olds have been attacked by the National Association for the Care and Resettlement of Offenders.
NACRO had hoped that the Crime and Disorder Bill could be amended at the committee stage of the House of Lords this week.
Baroness David, the Labour peer who chairs the all-party group for children, argued that strengthening the courts' powers would be counter-productive.
Past experience showed that removing young people from family and community life was likely to magnify their difficulties - nearly 90 per cent of juveniles leaving prison are back there within two years.
Meanwhile, the Government has brought into force secure training orders for 12 to 14-year-olds to the dismay of NACRO and other penal reformers. In opposition, Labour had agreed that secure training centres were a retrograde step.
Paul Cavadino, principal officer for NACRO, said most young offenders would be better dealt with by intensive supervision in their communities. "The few children of this age who have to be detained in a secure establishment should be held in local authority secure units which are part of the child care system, not in 40-place child jails."
And he is distressed by the Government's delay over ending the holding of remanded 15 and 16-year-olds in prison. "This practice has long been regarded as a recipe for criminal contamination, intimidation and all too often, self-harm and suicide attempts."
The plans of Jack Straw, the Home Secretary, appear to be more draconian than those of his predecessor, Michael Howard.
The Conservatives' 1991 Criminal Justice Act was to end custodial remands for under-17s, and give courts the power to remand 15 and 16-year-olds to local authority secure units instead, when places were available.
A building programme began for 170 places, with 100 intended for those on remand. Most of these have now been built, but in the meantime the harsher climate towards young offenders has sharply increased the number of juveniles remanded in custody. Numbers increased from fewer than 100 a day in 1993 to between 250 and 300 in 1997.
The new legislation will mean that local authority secure places built to end juvenile remands will be used to lock up 12 to 14-year-olds.
Mr Cavadino cites the recent report by Sir David Ramsbotham, chief inspector of prisons, which argued for the removal of all under- 18s from the "corrupting influence" of prison custody.
He found it particularly disturbing that the Bill gave the Home Secretary power to extend the detention and training order to children of 10 and 11. Local authority secure accommodation, where they were likely to be sent, held an increasing number of under-16s serving sentences for grave crimes such as murder, rape and robbery.