Guarded by four paramilitary police officers, the frail white-bearded Abu Bakar Bashir arrived at the hospital in Indonesia's capital this morning.
He appeared unable to walk unassisted and was helped into a wheelchair as photographers and TV cameramen jostled around him.
He was sentenced to 15 years in prison in 2011 for supporting a military-style training camp for militants that was uncovered the year before.
The octogenarian Bashir suffers from medical problems including chronically weak blood circulation. A copy of a prison memo seen by The Associated Press said Bashir is being treated for pooling of blood in the legs, a common condition in old age known as chronic venous insufficiency.
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In 2016 he was transferred from his isolation cell on the maximum security Nusa Kambangan prison island to Gunung Sindur prison about 50 kilometers southeast of Jakarta amid complaints from his lawyer of inhumane treatment.
Bashir's sympathisers hope Jokowi will grant him a permanent release due to his poor health, a move that would help mend fences between hard-line Muslims and Jokowi ahead of a presidential election in 2019 but would alarm allies such as the United States and Australia.
Jokowi's approval ratings remain high with the broader Indonesian public.
But prosecutors were unable to prove a string of terrorism-related allegations. He was instead sentenced to 18 months in prison for immigration violations.
Bashir has repeatedly denied any involvement in terror attacks and after being sentenced in 2011 for his role in the militant training camp said he rejected the ruling from "infidel" authorities.