By King-oua Laohong, Onnucha Hutasingh, and Kornchanok Raksaseri / Bangkok Post

With only half a square metre of space to accommodate each inmate crammed in a cell, many end up sleeping sitting up.

Overcrowding has become a new "punishment" for thousands of convicts in 143 prisons countrywide, as they outnumber the limited sleeping areas available to them.

Although the Department of Corrections stipulates that each male should have a 1.2m² area and each female a 1.1m² space, in practice these standards exist only on paper.

Thailand has roughly 360,000 inmates nationwide but a prison capacity of technically only 250,000. While some prisons have been able to expand and build new facilities, albeit under budget constraints, many have simply had to make do and reduce the amount of space each inmate has.

Even Justice Minister Somsak Thepsutin, when told about the problem at Ubon Ratchathani prison, found it hard to believe each inmate is given such little space to sleep in. He has since told all prison chiefs to check whether this is true.