Myanmar's junta has denied freeing an Australian academic detained for almost a year after Cambodia's leader Hun Sen on Monday took credit for arranging the release.

Economist Sean Turnell was working as an advisor to Myanmar civilian leader Aung San Suu Kyi when he was detained shortly after the coup in February last year.

He has been charged with violating Myanmar's official secrets law and faces a maximum penalty of 14 years in prison if found guilty.

On Monday, Cambodian Prime Minister Hun Sen said Turnell had "been released" the previous day.

The Cambodian strongman, who met with Myanmar's junta chief last month, claimed the release had happened after he passed on a request from Australia's government.

"At that time, I made the request to Min Aung Hlaing and Min Aung Hlaing said he would consider it positively," Hun Sen said, responding to questions about his trip to Myanmar.

"Yesterday, he was released," he added, referring to Turnell.

Junta spokesman Zaw Min Tun denied that Turnell had been released, but acknowledged that Hun Sen had brought up the matter during his visit -- the first to Myanmar by any foreign leader since last year's coup.

"Regarding this matter, Senior General Ming Aung Hlaing said he would think about it after his legal case is finished," he told AFP.

Turnell has appeared in court every Thursday in the military capital Naypyidaw for his trial -- where he is co-accused alongside Suu Kyi.

Human rights groups have raised concerns about his prosecution, particularly after the Australian embassy was denied access to his court hearing in September.

The exact details of Turnell's alleged offence have not been made public, although state television has said he had access to "secret state financial information" and had tried to flee the country.

AFP