Prisons might be full by the summer as the overcrowding crisis worsens, a report warned today.
The Prison Reform Trust study said the record jail population in England and Wales of 77,774 could be passed in "a couple of months".
Last October, prisoner numbers reached the all-time high - just 373 short of its absolute capacity.
The campaign group said that the figures had dipped over Christmas, but since the turn of the year the "pace began to pick up again".
The report said: "The annual Christmas slowdown in processing court cases pulled prison back from the brink of its capacity limit.
"From the beginning of 2006, the pace began to pick up again. Now the population is 77,004 - just a couple of months at the current rate of reaching a new historic high.
"What is now becoming an annual crisis in capacity looks set to hit earlier and harder in 2006."
It said many officials admitted privately that the prison system will be "entirely full" by the summer, with the prospect that prison doors would have to be temporarily closed.
A previous overcrowding crisis in 2002 led to inmates being kept in police cells at a far greater cost than normal prison cells.
The report added: "Prisons should be places that hold securely, and make effort to rehabilitate, serious and dangerous offenders.
"The skills and focus of those who run them should be wholly directed towards that aim in the interests of public safety.
"Instead, rapidly rising numbers have reduced many prisons to locked warehouses in which prison officers are called upon to act merely as turnkeys, processing people in transit from jail to overcrowded jail."
The reconviction rate of former inmates leaving overcrowded prisons in 2004 was 64%, compared to 51% to 1992, the report said.
Juliet Lyon, director of the Prison Reform Trust, told the BBC: "Overcrowding and reconviction rates are spiralling out of control.
"Unless government acts now to reserve scarce prison places for serious and violent offenders, the summer will collapse into a chaotic mess of police cells, pre-fabs, prison motorway vans and decommissioned hulks."Reuse content