The prison population in England and Wales reached a record high today.
The total number of prisoners hit 85,578, 83 more than the previous record of 85,495 set last October and just under 2,500 short of the usable operational capacity of 88,073, Ministry of Justice figures showed.
Criminal justice campaigners have called on the Government to reduce the number of people behind bars.
But last month Prime Minister David Cameron scrapped Justice Secretary Kenneth Clarke's "too lenient" plans to let offenders who plead guilty out of jail early.
Mr Clarke had proposed increasing the discount for the earliest guilty pleas from one third to a half in a bid to encourage more offenders to admit their crimes, saving costs and sparing victims the ordeal of a trial.
However, Mr Cameron forced him into an embarrassing U-turn after the plans came under fire from the Tory right and victims of crime.
A Ministry of Justice spokesman said: "We will always ensure there are sufficient prison places for offenders sentenced to custody by courts.
"There is currently a substantial margin between our available capacity and the actual population. New accommodation continues to become available and in the next 12 months 2,500 new places will become operational."
Frances Crook, director of the Howard League for Penal Reform, said: "As the prison population reaches an all-time high, it is more important than ever to address our failing penal policy.
"Every week we cram hundreds more people into our already bulging jails, only for people to leave prison unchanged and to go back to crime.
"Prisons are awash with drugs, violence and arson and this is inflicted on local communities when people leave prison.
"The answer to rising prison populations is not to build more failing jails. This ceaseless growth in prison numbers is untenable and I implore the Government to bite the bullet and find a strategic way to reduce the prison population by putting an end to short-term prison sentences.
"A record prison high is a sign of failure, not success."
Juliet Lyon, director of the Prison Reform Trust, said: "Let's make this the last record high population and instead look to a year on year reduction in prison numbers.
"Money spent on treatment for addictions would cut crime quicker than putting more people behind bars.
"Inflation in sentencing and lack of proper investment in alternatives to custody drive numbers up.
"The Legal Aid, Sentencing and Punishment of Offenders Bill, currently before Parliament, offers a rare opportunity to break this pattern. To do so it must bring to an end the injustice of sentences of imprisonment for public protection (IPPs), limit remands in custody to offences that could result in a prison sentence and remove mandatory minimum terms, leaving judges to pass fair and proportionate sentences in the full knowledge of the facts of each case.
"Most people would prefer a sensible system where the punishment fits the crime rather than have sentencing dictated by politics and headlines."