Patronised by the rich and powerful, the Phra Dhammakaya temple in Pathum Thani province and its abbot Phra Dhammachayo is under investigation for allegedly embezzling donations of nearly 800 million baht (US$24.6 million) since 1999.

The case was dismissed but in February the military-installed National Reform Council reopened it as part of its mission to reform Thai Buddhism.

Activist monk Luang Pu Buddha Issara supports the initiative. He said: “To fix this we cannot rely on the nation's Buddhist authority. Prime Minister Prayut Chan-ocha and the government must step in to fix this problem.”

The Supreme Sangha Council of 20 senior monks, which cleared Phra Dhammachayo of all wrongdoing, is under scrutiny.

Recent high-profile scandals in the Buddhist clergy have eroded trust between the public and Supreme Sangha Council, the main governing body of the Buddhist monks in Thailand. Many are calling on the government to step in and reform the organisation.

But some monks and their followers have opposed state intervention, arguing that monks who have to follow the 227 Buddhist precepts are better in making moral judgment than any layperson.

“The Supreme Sangha Council consists of senior monks who are well qualified spiritually to do their job. As for us laypeople with our unpolished minds, who are we to judge the conduct of monks?” said Pairat Limsirisetkul, Dhammakaya follower and former member of parliamentary subcommittee on religious affairs.

The government has insisted that reform can only take place if the monks themselves agree to the process.

Somchai Surachatree, spokesman for the National Office of Buddhism, said: “In religious affairs the monks govern themselves. The state has the duty to support and assist the monk order through the National Office of Buddhism. But we cannot step in to directly govern the monks.”

There is also a political dimension to the ongoing controversy with activists claiming that former Prime Minister Thaksin Shinawatra meddled in the case when he was in office.

“Back then Prime Minister Thaksin changed the state prosecutor in order to get the case dropped. This decision was then used by the Supreme Sangha Council to clear Phra Dhammachayo’s name,” said Luang Pu Buddha Issara.

Prime Minister Prayut is trying to maintain his political impartiality by insisting that the Supreme Sangha Council has the sole moral authority to judge the Buddhist clergy.

The Department of Special Investigation has summoned Phra Dhammachayo for questioning over allegations of fraud.