The Anti-Corruption Organisation of Thailand (ACT) on Sunday submitted an open letter to Justice Minister Somsak Thepsuthin, voicing opposition to the appointment of Supoj Saplom, a former permanent secretary for transport, to sit on a sub-committee tasked with studying a project for rehabilitation and development of inmates.
The appointment of Mr Supoj came only months after he completed a jail term for false asset declarations.
The ACT said in the letter that the constitution of Thailand bars people who lack morality, ethics and good governance from taking part in the country's administrative affairs.
Since people expect the Justice Ministry to be a model for righteousness and justice, it should appoint only people who are not tainted with corruption to work for it, the letter says. The appointment of Mr Supoj violates this principle.
Mr Supoj, the letter said, had just been released from a prison in a corruption case. Moreover, he is still facing more cases.
"The ACT believes that, in order to defeat corruption, everyone must be made to understand that it is disgusting and corrupt people should not be given a place in society. Therefore, the practice of giving a government official or politician convicted of corruption another role in government or politics is not acceptable to society," it said.
Mr Somsak, the justice minister, said last week that he had invited individuals from various professions, including former senior state officials, to give their input on the proposed establishment of an industrial estate for rehabilitation and development of inmates.
He gave a few names but did not mention Mr Supoj.
However, Mr Supoj, who served as permanent secretary for transport from 2009 to 2011, is among the names in the appointment order signed by Mr Somsak and available to the press,
Mr Supoj was released from prison in the middle of last year after serving 10 months for filing false asset declarations.