Several key figures of the People's Alliance for Democracy (PAD) will be among the 100 prisoners who will be released from jail on Friday, after His Majesty the King granted them royal pardons to mark his coronation.
They are Chamlong Srimuang, 83, Pibhop Dhongchai, 72, Somkiat Pongpaibul, 68, Somsak Kosaisuk, 72, and Suriyasai Katasila, 45.
Chamlong will be released from the Corrections Department's hospital, where he has been treated for various illnesses since February, while the rest will be freed from Bangkok Remand Prison, said Pol Col Naras Savestanan, director-general of the department.
Political activist Jatupat Boonpattararaksa, also known as Pai Dao Din, has been detained in Khon Kaen Central Prison since August 2017 for lese majeste. He has also been granted a pardon and will be released on Friday.
On Facebook, Wibul Boonpattararaksa, Jatupat's father, on Wednesday confirmed his son's impending release.
Mr Wibul said his son was granted parole and was actually scheduled to be released on May 16, but then Jatupat was given a royal pardon that will allow him to walk free on Friday.
Pol Col Naras said Sondhi Limthongkul, a key PAD protest leader, did not qualify to receive a royal pardon because he has also been sentenced for other offences that make him ineligible for a royal pardon.
However, Sondhi's prison term will be reduced. Another well-known inmate, Phaijit Thammarotphinit -- also known as Por Pratu Nam -- who was sentenced in June 2016 to 12 years in prison by the Supreme Court in a land encroachment case in Trat's Muang district, will also have his jail sentence reduced.
"Although Phaijit is an elderly prisoner who was supposed to be released under this royal pardon, he violated the Forest Act, which makes him ineligible for a royal pardon," said said Pol Col Naras.
Several prisons on Wednesday began releasing prisoners who were granted royal pardons. The provincial governor of Khon Kaen, Somsak Changtrakun, presided over a ceremony on Wednesday to mark the release of 146 male and 41 female inmates.
The province's local employment office set up a booth offering job placement services for the released inmates.