A Kent prison has been labelled one of the most overcrowded in the country by a leading reform group.
Canterbury Prison has 57% more prisoners than the charity advises
Canterbury Prison was named in a report published on Monday by the Prison Reform Trust.
The prison came eighth out of 90 prisons found to be overcrowded in the country.
It holds 57% more prisoners than the trust believes it should - and has only eight inmates fewer than the maximum possible number.
The situation has worsened since a report two years ago, which found it had 41% more prisoners than the trust recommended.
Geoff Dobson, deputy director of the Prison Reform Trust, said: "It imposes a lot of pressures on prison staff as well as the prisoners.
"It's not a healthy environment for anyone to be in."
The Prison Reform Trust has warned of "a serious crisis unfolding in jails across the country".
The current prison population of 73,379 is the highest-recorded level of inmates, reveals the charity, and it says that the UK locks up 139 people per 100,000 - the highest rate in the European Union.
A Prison Service spokesman told BBC News Online: "Whatever the population pressure the government is uncompromising in its response to serious and dangerous offenders.
"Where there is a need to protect the public, this will take place in a secure environment.
"Prison should be reserved for those serious, dangerous and persistent offenders for whom a custodial sentence is the only proper response.
"The government has made £60m available to provide an extra 740 prison places by March 2004.
"Two new prisons are planned within two years with a capacity to hold 1,290 inmates."