NATIONAL figures reveal three in four men’s prisons in England and Wales are overcrowded, with Usk and Prescoed prisons in the top 20.

Ministry of Justice (MoJ) data, analysed by the Howard League for Penal Reform, shows how prisons have been forced to cram more people into cells as prisoner numbers have grown and other jails have closed.

Between the end of January 2013 and the end of January 2015, the prison population, excluding immigration removal centres, rose from 83,062 to 83,680.

During that time Usk and Prescoed prisons (whose figures are combined) saw its prisoner numbers rise with 496 prisoners held on site, when it is designed for just 378.

In 2003, the prison was holding 482 prisoners.

The Howard League for Penal Reform said Cardiff and Swansea had “huge overcrowding problems” with the latter holding 422 but designed to accommodate 242.

Frances Crook, chief executive of the Howard League for Penal Reform, said: “Caging men in squalor with nothing to do all day is never going to help them become law-abiding citizens on release.

“Far too many people are being sent into already overcrowded jails and the need to stem the flow is now urgent.

“Government must get a grip on a prison system in crisis that is feeding the crime problem and creating more victims.”

Prisons Minister Andrew Selous said: "We always have enough space within our prisons to accommodate all offenders, and will never be in a position where we can't imprison those sentenced by the courts.

"All prisons have safe population levels and published statistics show that crowding is at its lowest levels since 2007/08.This Government has considerably increased the adult male prison capacity from the level inherited at the end of the last Parliament."

A Ministry of Justice spokesman added that ‘overcrowding’ is when two prisoners share a cell rather than having one to themselves, a solution that is commonly used and is “always done in a safe way”.