Shrewsbury jail is in the worst position, with 335 inmates behind walls designed to hold just 182, said the Howard League for Penal Reform.

Conditions in some prisons might be worse than the figures suggest because specific areas within them, such as those holding women or young offenders, are particularly overcrowded, said league director Frances Crook.

The young offender section at New Hall women's prison in West Yorkshire was at 203% capacity, holding 89 girls in space designed for 44.

The juvenile section at west London's Feltham Young Offenders' Institution, holding 15- to 17-year-olds, had 208 boys in accommodation built for just 100.

More jails are being built to cope with overcrowding

Ms Crook said 60% of jails had to feed and find beds for more people than they were designed to hold.

"Prisons are desperately over-full. Basic necessities of life have to be satisfied before it is possible to think about doing something to address offending behaviour.

"With prison numbers continuing to spiral out of control, overcrowding can only get worse," she warned.

Responding to the report, the Prison Service said reducing overcrowding was a key objective, but it was doing what it could to cope with rising numbers of prisoners.

Prisons and Probation Minister Joyce Quin said an extra �112m was being made available this year to increase capacity in the short term and make repairs.

She added: "At the same time the government is making available to sentencers a range of community punishments in which the courts and the public can have confidence."

Director General of the Prison Service, Richard Tilt, said: "A significant building programme means that capacity is increasing all the time. "