Min Zin, founder of the Institute for Strategy and Policy Myanmar (ISP-M), "has been subjected to criminal compulsory measures", Chinese foreign ministry spokesman Lin Jian told a news briefing.

Authorities are holding him "on suspicion of engaging in espionage activities that endanger China's national security", he said, without providing further details.

The ISP-M researches the political, resource and conflict dynamics of Myanmar, which was plunged into civil war by a 2021 military coup.

It is not clear whether Min Zin was conducting research at the time he was apprehended by Chinese authorities.

A person with professional ties to ISP-M, speaking anonymously because of the case's sensitivity, told AFP Min Zin was arrested on June 3 at Kunming airport in China's Yunnan province, which borders Myanmar.

"He went there to attend a meeting," said another person with a close relationship to the detained academic, also speaking on condition of anonymity.

Some ISP-M publications detail China's influence in the borderlands of Myanmar, where Beijing is accused of supporting both rebel factions and the military in pursuit of its interests.

The think tank is based in the northern Thai city of Chiang Mai, a hub for political exiles from Myanmar since the 2021 coup ousted the democratically elected government of Aung San Suu Kyi.

The junta ruled Myanmar directly for five years before staging tightly controlled polls that excluded Suu Kyi's party and delivered a walkover win for pro-military parties this year.

Lawmakers then voted for coup commander Min Aung Hlaing to take over as president, a transition that democracy watchdogs and analysts -- including some at the ISP-M -- have derided as civilian rebranding of military rule.

China, however, was an enthusiastic backer of the election and on Friday announced Min Aung Hlaing will arrive on a state visit next week and meet with his counterpart Xi Jinping.

The visit, which begins Monday, will be Min Aung Hlaing's first to China since taking over the role of civilian president.

Chinese authorities said the US consulate in Guangzhou had been notified of Zin Min's case.

"His family and colleagues are following up with the consulate office there," the source close to Zin Min told AFP. "I know his family is worried."

Neither the US State Department nor the ISP-M have responded to a request for comment.