The home secretary's plans to build more prisons have been condemned as "desperately short-sighted" after new figures show they will fall far short of the numbers needed.
John Reid last week announced the building of 8,000 more prison places in England and Wales, taking the total up to almost 90,000 by 2012.
But the latest projections from the Home Office suggest the prison population could stand at a maximum of 102,280 by that time - leaving 10,000 prisoners with nowhere to go.
"These new projections completely blow Mr Reid's plans out of the water," said shadow home secretary David Davis.
"All we have had is more bluster, just like the three previous home secretaries who talked tough but created the disaster we see today."
Liberal Democrat home affairs spokesman Nick Clegg said the figures painted a picture of "chronic and worsening prison overcrowding" - something prison campaigners warn is already a major problem.
"John Reid's promise to build more prison spaces has been exposed as desperately short-sighted and ignorant of the facts," he said, adding: "Until we work out effective ways to turn prisoners away from crime, there is no way the prison system will be able to cope."
The total prison population increased from 51,080 in June 1995 to 76,190 ten years later, and at the end of last month, it stood at 77,980 - up 2.4 per cent on a year ago.
Campaigners warn that as prisoners are forced to share rooms and facilities, the chances of them being properly rehabilitated and prevented from reoffending are dramatically reduced. Currently, half of all offenders go on to commit crime again.
"It is too late for the home secretary to build his way out of trouble," said Juliet Lyon, the director of the Prison Reform Trust.
"He can either bankrupt the country building prisons, or tackle the drug addiction, alcohol-fuelled disorder and neglect of mental illness that are causing this hyperinflation of men, women and children in our prisons."
Announcing the new prison places last week, the home secretary said they would ensure the most dangerous criminals were locked up for longer, but also revealed plans to deal in other ways with people who did not need to be put in jail.
Foreign prisoners would automatically face deportation to "stop them clogging up the system", Mr Reid's review stated, while less serious non-violent offenders would be handed community sentences "that ask a lot of them".
There were also too many people with mental health problems in jail, it said, and proposed to improve the numbers of those who were not dangerous being treated in the community.