Thousands upon thousands of mourners are taking part in prayers during the second day of the funeral ceremony.
Mojtaba Khamenei has not appeared in public since the deadly attack at the start of the war in January. He may have been injured in the same attack, but if so, it is not known how serious his injuries are.
On Sunday, Khamenei's coffin will be moved from the stage where it has been on display since Saturday, to be taken in procession through the capital on Monday.
Television broadcasts show that President Masoud Pezeshkian has attended the ceremony along with other dignitaries, including Iran's chief negotiator Mohammad Bagher Ghalibaf.
