An Australian economist jailed in Myanmar has been moved from the isolated military-built capital to a sprawling prison in Yangon, a source with knowledge of the case told Agence France-Presse (AFP) on Monday.

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

In September, he and Suu Kyi were convicted by a closed junta court of breaching the official secrets act and jailed for three years each.

"Mr Sean Tunell was moved to Insein prison," a source with knowledge of the case told AFP, without specifying when the academic had been shifted.

AFP has asked the Australian Embassy in Yangon for comment.

Turnell's three-year term is eligible for a time served deduction, according to legal sources, meaning the Macquarie University professor is more than halfway through his sentence.

Turnell, the first foreign national known to have been arrested following the Feb. 1 coup, was in the middle of a phone interview with the BBC when he was detained.

"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," he told the broadcaster at the time.

The exact details of his alleged offense have not been made public, although junta-controlled state television has said he had access to "secret state financial information" and had tried to flee the country.

Journalists were barred from the court proceedings and defense lawyers were slapped with a gag order that prevented them from talking to the media.

More than 2,200 people have been killed and 15,000 arrested in the military's crackdown on dissent since the February 2021 coup, according to a local monitoring group.

Hundreds of political prisoners are estimated to be held in Yangon's sprawling Insein prison, including foreign nationals.

Former U.K. Ambassador to Myanmar Vicky Bowman is serving a one-year sentence there for failing to declare she was living at an address different from the one listed on her foreigner registration certificate.

Japanese journalist Toru Kubota, who was jailed for 10 years after being arrested at an anti-coup protest, is also held in the colonial-era complex.