Jakarta - Five Australians jailed for immigration offenses after landing a small plane in Indonesia's eastern-most province of Papua have been acquitted on appeal, their lawyer said Tuesday.

In January, a court in Merauke district sentenced the Australians to two and three years in prison respectively after convicting them of landing a plane illegally and entering Indonesia without visas in September.

"The appeals court accepted our argument that our clients obtained permission to land," defence attorney Efrem Fangoihoy said.

Fangoihoy said his clients could leave Indonesia as early as Wednesday.

They were released from prison and put under city arrest last week pending a decision on their appeals.

The Australians said they had flown to Papua to explore tourism business opportunities and assumed they could get visas on arrival.

Papua is home to a low-level separatist insurgency and visa on arrival regulations are only applicable at major ports. (dpa)