The anti-corruption body has defended its move against former prime minister Yingluck Shinawatra over mismanagement causing the 2011 floods, saying her predecessor ex-PM Abhisit Vejjajiva will also be probed.
Sansern Polchiak, secretary-general of the National Anti-Corruption Commission (NACC), said the case was based on old complaints that the governments led by the pair had mismanaged the situation in 2010-11, resulting in one of the largest floods in Thai history.
"We aren't trying to find fault with Ms Yingluck. Mr Abhisit will also be investigated and we ensure the investigation will be fair," he said.
Mr Sansern also said Supa Piyajitti, an NACC commissioner, had asked to pull out of one of the six panels she chaired in the 15 cases it is probing against Ms Yingluck.
The panel will look into Ms Yingluck's refusal to have a government agency disclose the benchmark prices in a procurement as proposed by the NACC.
Ms Supa said she pulled out of this case because she was formerly a deputy finance permanent secretary in charge of supervising government procurement so there might be a conflict of interest.
Mr Sansern said Ms Supa was handling six of the 15 cases the NACC is reviewing against Ms Yingluck because all of them involved politicians, the area under the supervision of Ms Supa.
Earlier this week, Ms Yingluck filed a petition with the NACC asking for the removal of Ms Supa from her cases.
Ms Yingluck's lawyer reasoned Ms Supa was a prosecution witnesses in a criminal case against her involving the rice-pledging programme so it was not fair to her that Ms Supa should lead the investigation into other cases against her.
He also claimed Ms Supa used to head a Finance Ministry panel closing the accounts of the rice programme and under her watch some insider information was leaked to the opposition.