John Reid's emergency jail expansion programme has been likened by the prison watchdog to Noah building his ark after the flood began.
Anne Owers increased the pressure on the Home Secretary, by accusing ministers of ignoring repeated warnings that a "serious crisis" in the prison system was imminent.
The Chief Inspector of Prisons warned that jails were becoming dangerous, rehabilitation work with offenders was suffering and many inmates were housed in appalling conditions. Unveiling her fifth annual report, Ms Owers used her strongest language since becoming chief inspector to query the Government's entire approach to penal policy. Her criticism is likely to be echoed in a keynote speech tomorrow on criminal justice by Rowan Williams, the Archbishop of Canterbury. With the jail population in England and Wales at a record 80,000, Mr Reid is looking for extra spaces to hold the increasing numbers of offenders in custody. He wants to house hundreds in temporary accommodation, but Ms Owers said she was worried they would be filled as soon as they were opened. She said: "It is normally considered good practice to build an ark before the flood rather than during it or after it."
She added that she was not just referring to prison-building, but the work rehabilitating offenders and minimising the risk in prisons. "This means long-term planning. Planning which in my view should have happened a long time ago."
Ms Owers admitted she could not see an easy way out of the situation, adding: "We're driving towards a position where we simply can't accommodate everybody. We certainly won't be able to throw up buildings in time to do so." She suggested that finding alternative punishments for women and more appropriate treatment for mentally-ill offenders could ease the pressure on jails.
And she protested over the number of foreign prisoners held in custody awaiting deportation and the lack of planning for inmates serving the new "indeterminate" sentences. Although she praised work in prisons on education, training and resettlement, her overall picture was of a system at breaking-point.
She warned that the unparalleled increases in the prison population and the squeeze on public spending was "an alarming and potentially extremely damaging combination". She said: "We have seen too many local prisons recently whose cultures and practices are sliding back, or failing to improve. These are only straws in the wind - but the wind does not appear to be blowing in the right direction."
Following a meeting between Ms Owers and Mr Reid yesterday, a Home Office spokeswoman said: "He shares her views and concerns across a number of issues and is actively engaged in addressing the problems she raises."
David Cameron, the Tory leader, said his party had been warning the Government for years. "It needed to make available more spaces in prisons so that we can make sure prisons rehabilitate, turn around and educate and train people."
The Tories also seized on a minister's refusal yesterday to deny that Gordon Brown tried to persuade the Home Office to control costs by keeping offenders out of jail. Stephen Timms, the Chief Secretary to the Treasury, was asked by MPs whether the Chancellor was responsible for the prisons crisis. He replied: "It's perfectly clear to the Home Secretary, as it is to everyone else in the Cabinet, that they need to manage their department within the settlement as agreed."