Indonesian authorities said Monday they believe a protest planned by Muslim hardliners next month in the capital may be a guise for treason and are warning the organisers against holding the rally.

The protest planned for December 2 is to demand the arrest of Jakarta's minority-Chinese governor, Basuki 'Ahok' Tjahaja Purnama who is being investigated for alleged blasphemy after he spoke about a passage in the Koran that prohibits Muslims from electing non-Muslims as leaders.

National police chief Gen Tito Karnavian and military chief Gen Gatot Nurmantyo said at a joint news conference they have received credible information about the possibility of treason behind the planned rally.