Anne Owers, the Chief Inspector of Prisons, said demands for longer sentences had led to a prisons "crisis" which was boosting the suicide rate.
In a stark warning to ministers, the Tory opposition and the right-wing media, the prisons watchdog has urged them to "be responsible" and not to create climates where the courts feel pressured to recommend prison terms for non-violent offences.
"If you lock up this number of people this is the consequence. This is what is going to happen: more people are going to die in our prisons but also our prisons aren't going to be able to do the positive stuff nearly so well," she said. "This is what is happening. So everybody who is responsible - be responsible."
Her remarks, in an interview with The Independent, came as prison numbers last week reached a record level of more than 77,000, near capacity.
Ms Owers said the overcrowding "crisis" meant prisoners were "bussed" around the prison estate in search of space. "It is like some sort of horrific game of musical cells," she said.
In a damning assessment of the overcrowded penal system, she said prisons were so full that programmes to cut offending were compromised, leaving jails to "recycle people".
"All the research on patterns of sentencing shows that we are sentencing people to prison more often for things that would not have attracted a custodial sentence before and when we send them to prison we are sending them to prison for longer," she said.
Her remarks came as Lord Woolf, the Lord Chief Justice, called for the courts to look more closely at restorative justice as an alternative to prison. Last week Andrew Sims, a 19-year-old on remand at the Glen Parva young offenders' institution, became the 50th prisoner to kill himself this year. Last year 96 people killed themselves in prison and 228 prisoners were resuscitated. There were also 17,678 cases of self-inflicted harm.
The prisons watchdog said the fall in the number of women in prison had coincided with a sharp drop in suicides. Last year women prisoners were twice as likely to kill themselves than men, and female suicides were increasing. This year only two women have killed themselves. "You can't but draw a conclusion from the fact that the suicide rate was lower in the first part of this year. There was a definite dip and a very welcome one," she said. "If you look at women's prisons, we have some space and not quite such a pressured environment."
The drop in female prisoners follows a call by politicians, including Tony Blair, to consider alternatives to jail for women. The Prime Minister's wife, Cherie Blair, has campaigned publicly to cut the number of women going to prison for non-violent crimes.
Ms Owers acknowledged that the rhetoric from Government had contributed to the cut in numbers. "I think it probably has helped to create a climate where sentencers will quite rightly consider all the other options before using prison as a last resort," she said.
By Kunal Dutta
* Over the past 10 years the number of prisoners in England and Wales has increased by 25,000.
* More than half of the 142 prisons in England and Wales are overcrowded, Home Office figures show.
* By the end of July, more than 10 per cent of these were full even beyond their "safe" limits.
* More than 17,000 prisoners are being held two to a cell designed for one.
* Since the start of June, more than 90 per cent of prison suicides have involved prisoners in overcrowded cells.
* In 2004 there were a total of 95 suicides in England and Wales, a record number.
* By the end of July, Liverpool's Altcourse prison was holding 933 offenders in cells designed to hold 614.
* Prison Service research shows that 10 out of 20 prisons with the highest rates of suicides are also in the top 20 for population turnover.
* Last year, the average pay for employed prisoners was £8 per week.
* In 2003 and 2004, the average amount of time spent on purposeful activity by prisoners in the 11 private prisons in England and Wales was 26.7 hours - 3.5 hours longer than in public-sector prisons.
* There have been seven prisons ministers since Labour took power in 1997.
* In 2003-04 it cost an average of £37,305 to keep a person in prison.
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