The Justice Ministry has instructed the Corrections Department to collect DNA samples from inmates to verify the identities of prisoners.
The process will start once the government agrees to pass a new law to allow for the collection.
Justice Minister Gen Paiboon Koomchaya says he will allow the Central Institute of Forensic Science (CIFS) to collect the DNA.
Pol Col Dusadee Arayawut, deputy justice permanent secretary, disclosed the move as he presided over a meeting with the Corrections Department yesterday.
Doubts have been raised in the past about the identities of those who are put in jail, he said.
The idea for the collections started after a report emerged that a prisoner found dead behind bars recently was not in fact the person he was thought to have been, as his identity was different from that which the jail held originally.
The DNA will also be used to verify the identity of anyone who dies in prison, Pol Col Dusadee said.
The collection process will boost public confidence that the people in jail are the ones who were convicted of a crime, Pol Col Dusadee said.
Although the department has collected the fingerprints of detainees, some records for inmates who have spent years in jail may no longer exist.
Pol Col Dusadee also asked the department to roll out regulations to collect the DNA of inmates along with the DNA found on mobile phones discovered during jail raids.
The department also plans to start collecting DNA samples before convicted suspects are sent to jail, he said.
DNA can be just as useful as a witness, CIFS chief Porntip Rojanasunan said.
Department director-general Witthaya Suriyawong said there are more than 300,000 people in the country's prisons.
Inmates jailed for drug offences will be used in a pilot project for the scheme.