Australia's second most-senior military officer has called for the "immediate release" of detained Australian economist Sean Turnell during a second phone call with a top member of Myanmar's military junta, ABC reported.

The Vice Chief of the Australian Defence Force, Vice Admiral David Johnston, spoke with the Deputy Commander in Chief of the Myanmar military, Vice Senior General Soe Win, on Wednesday.

The conversation occurred a week before the economist is due to face court alongside its ousted leader Aung San Suu Kyi for allegedly violating the official secrets act.