This probe could potentially cause a new scandal for the military government, which has promised to rid Thailand of corruption, although experts have said the country has failed to tackle a culture of impunity for the rich and powerful. 

The Office of Public Sector Anti-Corruption Commission (PACC) said on Tuesday it had come across evidence of irregularities amounting to about 100 million baht ($3.2m).

The secretary-general of the office Korntip Daroj told Reuters: “We have found that there are corrupt practices involving money destined for low-income people which the state allocates every year.

“We have investigated and found corruption-related instances and evidence in about 49 out of 76 provinces.”

Prime minister Prayuth Chan-ocha said he ordered the dismissal of all those involved in the case and called for an investigation by the ministry.

The funds, given directly to the poor in grants of up to 3,000 baht ($100), are disbursed through the Social Development and Human Security Ministry.

Chan-ocha, who leads the junta government which took power in 2014, told reporters after a cabinet meeting that the government had always been strict about corruption.

He said: “I don’t want you to think that it has become worse.”

His deputy Prawit Wongsuwan is also under investigation for failing to declare among his assets a collection of luxury watches.

Thailand is ranked 96 out of 180 countries in Transparency International’s Corruption Perception Index 2017, slightly better than the year before.