Sean Turnell, an Australian adviser to Aung San Suu Kyi appeared in a junta court to face immigration and official secrets charges, a lawyer involved in the case said Thursday.

Macquarie University professor Sean Turnell was the first foreign national arrested following the February 1 coup that ousted Suu Kyi's government and sparked huge protests.

Turnell has been held at Insein Prison in Yangon since his arrest and appeared "frail and tired" in court in the capital Naypyidaw, said lawyer Khin Maung Zaw, who is working on the case.

Turnell was wearing a "full Covid-19 protective outfit", the lawyer added, without giving precise details.

In July his wife pleaded for his release, citing worries about his health as the country endured a surge of Covid-19 cases.

Pictures of Turnell allegedly receiving a vaccine in Insein Prison later appeared in state-run media.