Sean Turnell was working as an adviser to Myanmar's civilian leader Aung San Suu Kyi when he was detained shortly after the coup that ousted her government in February last year.

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

Since seizing power, Myanmar's military government has detained thousands of pro-democracy protesters, with many facing secret trials that rights groups have decried as politically motivated.

Turnell and co-accused Aung San Suu Kyi had earlier appeared at weekly hearings in a special court in a municipal compound in the sprawling capital.

But both would appear on Thursday at a "special court in Naypyidaw prison", said a source with knowledge of the case, without giving further details.

A junta spokesperson could not be reached for comment.

Hearings for Aung San Suu Kyi's numerous other trials -- which could see her sentenced to more than 150 years in prison -- have already been transferred to the same prison compound, a source told AFP on Tuesday.

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.

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

Turnell was in the middle of a phone interview with the BBC when he was detained after the coup.

"I've just been detained at the moment, and perhaps charged with something, I don't know what that would be, could be anything at all of course," Turnell told the broadcaster at the time.