Sir David Ramsbotham wants more cash for the prison service

Sir David said: "Overcrowding is not just a question of the number of cells in which you can put people, it's all the other things."

"It's not just locking them up and doing nothing with them."

He said it was about whether there were enough workshops, educational projects, drug treatment and offending behaviour programmes as well as if there were enough people to staff the programmes.

"The answer is, on the whole, `no'," he said.

Efficiency savings

He attacked the Treasury for demanding efficiency savings from the prison service at a time when it needed more money to cope with an increase in prisoner numbers.

Sir David, who steps down next year, said no-one knew how much money the prison service needed to focus on preventing criminals from re-offending.

"Let's have a proper re-examination of the role and the cost of imprisonment," he said.

No-one knows the cost of imprisonment

The prison population in England and Wales is currently 62,229 - a higher per capita rate than any western European country except Portugal.

Sir David's comments follow Conservative leader William Hague's suggestion that more offenders should be locked up, while the Lord Chief Justice, Lord Woolf, called for a cut in the prison population.

Lord Woolf said on Wednesday that overcrowding of prisons was a "cancer" that undermined the work of the prisons.

Political pressure

The leader of Britain's barristers has supported Lord Woolf in his plea for politicians to stop playing the "prison card".

Chairman of the Bar Council Roy Amlot QC said barristers were becoming "increasingly concerned" at the expansion of the prison population and politicians' attempts to pressurise the courts into locking up more offenders.

"We are anxious that balance is maintained and that judges are allowed to use their discretion."

He added: "Politicians are never in the best position to judge what should happen in the courtroom."

Mr Amlot also said the Bar Council was opposed to mandatory sentences, such as the three-strikes-and-you're-out provision for an automatic three years' jail for repeat burglars.

Since its introduction last year it has not yet been implemented.