An Indonesian court has heard the start of an appeal by jailed radical Islamic cleric Abu Bakar Bashir to have his conviction overturned.

The 77-year-old leader of the Jemaah Islamiyah militant network filed a judicial review of his 2011 conviction when he was sentenced to 15 years in jail for setting up a terror training camp in Indonesia's province of Aceh. A higher court later cut the sentence to nine years.

Bashir read out his appeal before the District Court in the central Java town of Cilacap, arguing what he was doing then was merely a practice of worship.

The hearing will resume Jan. 26 with a response from the prosecutors and to hear any testimony from witnesses.