The prison population in England and Wales reached a record high yesterday.
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 an effort to encourage more offenders to admit their crimes, saving costs and sparing victims the ordeal of a trial.
However, Mr Cameron forced him into a U-turn after the plans came under fire from the Conservative right and victims of crime.
A Ministry of Justice spokesman said it would "always ensure there are sufficient prison places".
"There is 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: "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."