Corruption is estimated to cause 50-100 billion baht in damage to the Thai economy each year, according to a research panel formed by the Public Sector Anti-Corruption Commission (PACC).
It is a combined loss from 14 corruption categories based on the survey on the 2018 fiscal year, said Sangsidh Piriyarangsan, chairman of the panel, terming this as "economic corruption".
The 14 categories include bogus marriage certificate registrations between Thais and foreigners, embezzlement of the old-age fund for the elderly, embezzlement cases involving state enterprises, and unlawfully adding names into house registrations.
PACC chairman Kitti Limchaikij said his agency has received more than 30,000 graft complaints since the watchdog was formed 10 years ago, adding most of the cases were committed by state officials.
Another newly discovered case concerns procurements handled by the provincial offices of the Office of Basic Education Commission (Obec) in the far South, Mr Sangsidh noted.
As the offices are in the insurgency-plagued deep South, no one dared to go to the areas to investigate them, he said.
High-ranking officials in various agencies were found to have exploited the southern violence for their personal gain, he said, adding special laws imposed in the region were also conducive to malfeasance without proper scrutiny.
Malfeasance can be detected in the central, regional and local administrations, he said, adding in Thailand, corruption appears to be more likely in small-scale projects. Although they are small-scale projects, the losses can also be substantial, Mr Sangsidh said.
"The reason why the corruption problems rose rapidly is because of the closed political system, in which any agency can proceed without scrutiny," said Mr Sangsidh.
Corruption at local level contributed to unfair business competition and damage to the country's economy, Mr Sangsidh said.
Governments that wield strong power -- regardless of whether they are democratically elected or not -- tend to engage in corruption more often, he added.