Beirut: Lebanon's military court has acquitted one of four Australian brothers accused of planning to blow up a flight from Sydney to Abu Dhabi nearly two years ago, his lawyer said on Thursday.

State news agency NNA said the Lebanese-Australian man, Amer Khayat, would be released from Lebanon's Roumieh prison, where he has spent two years and two months.

His lawyer, Jocelyne al-Rai, said legal procedures for him to leave prison were being completed. "It took time for his innocence to be revealed," she added.

The plot involved smuggling a bomb in a meat grinder onto an Etihad flight leaving Sydney Airport. Credit:Kate Geraghty

The military court also sentenced three other Khayat brothers - Khaled, Mahmoud and Tareq - in absentia to hard labour for life, NNA said.