The commemoration ceremony of Sheikh Zakzaky will be held at the shrine of Hazrat Masoumah (AS) in Iran's central city of Qom on Thursday.
Ayatollah Mohsen Araki, a member of the Assembly of Experts, plans to deliver the keynote address at the ceremony.
Sheikh Zakzaky has been held in detention since December 2015 and was charged just in April 2018 with murder, culpable homicide, unlawful assembly, disruption of public peace and other accusations. He has pleaded not guilty.
In 2016, Nigeria’s federal high court ordered his unconditional release from jail following a trial, but the government has so far refused to set him free.
The top cleric, who is in his mid-sixties, lost his left eyesight in a raid which was carried out by the Nigerian army on his residence in the northern town of Zaria in December 2015.
During the raid, Zakzaky’s wife sustained serious wounds too and more than 300 of his followers and three of his sons were killed. Zakzaky, his wife, and a large number of the cleric’s followers have since been in custody.