A survey of the entire inmate population of Thai prisons is to be conducted in an attempt to identify prisoners who might have been wrongly imprisoned, following a call by Justice Minister Charnchai Likhitjittha for prison reforms.

Corrections Department director-general Natthee Jitsawang said yesterday the survey would focus first on those convicted after undergoing trials from lower courts through to the Supreme Court. A rough figure for the number involved was expected later this week.

Natthee said he believed very few of these prisoners would have been jailed without having committed the crimes for which they were convicted.

"The survey needs to be done very effectively and carefully in order not to let those who really did wrong back on to the street," he said.

Inmates who are screened initially will then be interviewed to find out whether they can provide credible claims of innocence, possibly based on new evidence which might have become available after their trials.

If they can provide such claims, a recommendation from the Corrections Department certifying their statements will then be issued along with the inmates' affidavits, before a further process is begun by Justice Ministry officials, Natthee said.

Charnchai raised the idea last week, based on his concern that a large number of prisoners might have committed crimes out of foolishness, due to their lack of education, or out of financial desperation, because they come from poor families.

Natthee said rehabilitation programmes were already provided to inmates at all prisons according to the nature of the crime they had committed, such as sex education and adjustment of attitudes towards women for male sex offenders. Skills training was automatic for all inmates, regardless of the crimes for which they had been imprisoned.

The director-general said inmates' profiles show that repeat offenders mostly committed petty crimes, such as theft, which carry short prison terms. Rehabilitation programmes for these inmates need to be longer to be effective in changing their behavioural patterns.