Footage showed Khamenei’s coffin, bearing the colours of the Islamic Republic, being carried aloft at the Grand Mosalla on Friday.
Iran’s President Masoud Pezeshkian was among those paying their respects after the coffin was placed at the vast religious complex.
Pakistan’s Prime Minister Shehbaz Sharif, whose country has mediated peace talks between the US and Iran, former Russian president Dmitry Medvedev and the Afghan Taliban’s Foreign Minister Amir Khan Muttaqi were also in attendance.
Six days of ceremonies will start at 06:00 (03:30 BST) on Saturday, at Tehran’s Imam Khomeini Mosalla, which visitors can visit to pay their respects until Sunday afternoon.
There will be an official funeral ceremony in Tehran on Saturday, which the Tehran-based Mohammad Rasulullah Corps is leading.
The group’s commander Hassan Hassanzadeh said Khamenei’s coffin would be displayed on an elevated platform, with crowd flows designed to allow visitors to enter and leave within 15 to 20 minutes.
Khamenei’s body will lie in the Grand Mosalla for three days, alongside the remains of family members who were also killed in the US and Israeli strikes in February.
