The UK's leading prison reform charity has slammed a £280 million Budget cash boost for the government's drive to lock up young offenders.

Gordon Brown yesterday awarded an extra £180 million to an existing £100 million earmarked for secure and prison accommodation.

The Howard League accused the government of pursuing an "obsession" with locking up child offenders - and it warned that the new drive could lead to the deaths of more youngsters in custody.

The cash, described as "excellent news for everyone" by the home secretary, will provide 2,300 new prison places and the expansion of new secure accommodation for persistent child offenders as young as 11.

The building of new 40-bed prison units will begin next month as the jail population, at a record 70,200 inmates, is just days way from "bust point".

"The extra funding will ensure the police are not faced with a choice between fighting terrorism or fighting street crime" said Blunkett.

"It also means that when the courts decide that criminals need to be locked away - be they adults or persistent juvenile offenders - we have appropriate accommodation capacity to provide the security, treatment and rehabilitation needed."

The pledge to fund extra jails came as the Howard League mounted a High Court challenge over the treatment of children in prisons.

"The Howard League deplores the plans to waste public money by building thousands of additional prison places for children," said the league's director, Frances Crook.

"The crime rate is going down, yet the home secretary is talking the prison population up, and the cost to the taxpayer is consequently going through the roof. It is extraordinary that politicians seem unwilling to accept success."

The penal reform charity is warning that the government's approach could lead to an increase in jail suicides amongst youngsters.

"The Howard League questions the legality of his plans to incarcerate children on remand when an adult would get bail," said Crook.

"Four young teenagers took their own lives in prisons, and more will die because of the home secretary's mistaken obsession with locking up children."