Thailand's corruption ranking has plummeted, from 76th in 2015 to 101st among the 176 countries assessed in 2016 by independent watchdog Transparency International.
The watchdog attributed the drop to government repression, lack of independent oversight, entrenched military rule, deteriorating rights and a banned opposition.
In releasing its Corruption Perceptions Index 2016, the corruption watchdog said on Wednesday that Thailand's score dropped from 38 points out of 100 in the previous year to 35 as government repression, lack of independent oversight, and the deterioration of rights eroded public confidence in the country.
Its ranking fell from 76th out of 168 countries assessed in 2015 to 101st out of 176 countries in 2016, equal with Gabon, Niger, Peru, the Philippines, East Timor and Trinidad and Tobago.
Thailand's new constitution, while it placed significant focus on addressing corruption, entrenched military power and unaccountable government, undermining eventual return to democratic civilian rule, it said.
Free debate on the constitution was impossible; campaigning in opposition was banned and dozens of people were detained. The military junta also prohibited monitoring of the referendum, Transparency International said, referring to the constitutional referendum in August last year.
In Asia-Pacific, Thailand and Cambodia both fell in the rankings.
Cambodia, for the second year in a row, was rated the most corrupt Southeast Asian country on the list with a score of 21 points. As space for civil society continued to be extremely restricted, that was not surprising, Transparency International said.
Over two-thirds of the 176 countries and territories fell below the midpoint of the scale of 0 (highly corrupt) to 100 (very clean). The global average was 43 points. Top scorers were Denmark and New Zealand and the lowest was Somalia.