Cherie Blair hits out at state of crowded prisons

Cherie Blair will declare tonight that many inmates of British jails should not be inside at all, after her own investigation of the prison system.

In a speech to be given in London, the Prime Minister's wife will describe how she has toured some of the country's most infamous jails and interviewed prisoners including drug dealers, inmates with mental health problems and young offenders.

She will tell her audience that the sheer scale of the jail population – revealed by Home Office ministers this week to be within 300 of the service's full capacity – is "crippling" the prison system in England and Wales.

"The huge increase in numbers and the prevalence of short-term sentences is crippling to any attempt at a constructive approach to prison," she says.

The comments in the inaugural Longford Lecture, which is in memory of the social and penal reformer Lord Longford and sponsored by The Independent and the Prison Reform Trust, will put Mrs Blair back in the political arena.

Her comments last month in which she said Palestinian suicide bombers had "no hope but to blow themselves up" prompted such an outcry that she issued a statement of regret.

But, speaking as a leading employment law and human rights barrister, Mrs Blair will express her deep concern that the prison population contains large numbers of unsentenced prisoners and many mothers of young children.

In a speech entitled "The Law, The Victims and The Vulnerable", she says: "It is particularly worrying that more than one in six of the current prison population is on remand – in other words they have yet to be tried or sentenced. In fact, the majority of this group doesn't ultimately go on to receive a prison sentence."

She calls on society in general, and the criminal justice system in particular, to take a more positive view of community-based sentences as an alternative to prison.

She also advocates the use of American-style "community courts" designed to help offenders and to make them repay a debt to their neighbourhood.

Mrs Blair highlights research that she says shows the "especially serious" impact of prison on women. "Not least because nearly half of all women prisoners have children living with them before coming to prison – an estimated 10,000 children are affected each year," she says. "A third of these children are under the age of five and two thirds are under the age of 10. A significant number of these families are permanently broken as a result of the mother's imprisonment, and as many as four out of 10 lose their homes."

Mrs Blair talks of her experiences during a recent tour of prisons in London and Liverpool, where she met inmates, prison officers and jail chaplains. At Holloway women's prison in north London, Mrs Blair was "shocked" by "the enormous number of women prisoners who report having suffered a history of violence and sexual abuse".

She said that a "drug pusher" at another jail had explained to her that a prison-based drugs counselling course had helped him to understand the damage caused by his criminal activities.

Mrs Blair called on drug addicts to be given better support upon their release from jail. "There is little point in drying out addicts in jail only to send them unsupported back into the community. Vulnerable people leaving prison must be helped to stay away from their old patterns of life," she said.

The prison population stands at a record 71,360 – just 293 short of its capacity.