Around 30 complaints have been submitted to the Public Sector Anti-Corruption Commission (PACC) by foreign tourists and business operators claiming they were badly treated by Thai authorities.
PACC secretary-general Korntip Daroj said Thursday of the 30 complaints, two have been probed by disciplinary sub-panels set up by the agency on Wednesday.
The first case involved Sa-ngob Homsombat and Pairot Thinno, two former City Hall tessakit (city inspectors) who demanded money from a tourist in the Klong Lod area of Bangkok's Phra Nakhon district in 2016.
City Hall later sacked the two officials.
"Despite their dismissal, the PACC will still proceed with disciplinary and legal action against both of them," he said.
The second is related to Australian tourists who were physically assaulted in Phuket's Kratu district in 2015. Australian authorities later sought help from the PACC regarding the case.
Lt Col Korntip said all complaints were lodged with the agency's complaint centre which was established under a bilateral agreement with the Hong Kong-based Independent Commission Against Corruption (ICAC).
The centre aims to provide assistance to foreigners, particularly business operators, who face problems in Thailand.
He said the agency has received complaints via the centre from people of various countries including Singapore, Hong Kong and South Korea.
The complaints mainly involved state officials demanding bribes, committing assaults, making verbal threats and even trafficking drugs.
Lt Col Korntip said efforts would be made to restore confidence among foreign business operators.