Iranian mourners called for revenge as crowds packed central Tehran for the start of the funeral of Ayatollah Ali Khamenei.

The doors of the Grand Mosalla prayer complex opened at 6am local time to mourners who had gathered from the night before.

Mr Khamenei’s coffin, wrapped in an Iranian flag, was placed on a raised platform alongside the coffins of family members killed in the same attack, as mourners filed past to pay their respects, separated into men’s and women’s routes.

A small coffin of his 3-year-old granddaughter was also on display. She was killed by American and Israeli missiles on Feb 28, along with her family members on the first day of the war.

Above the platform hung a banner bearing a Quranic verse: “Say, I give you but one admonition: that you rise up for God, in pairs or singly” – the scriptural root of the ceremony’s slogan, “One must rise.”

At points, the crowd beat their chests and chanted, “Revenge, revenge,” and “Death to America.”

State television zoomed in on a banner in the crowd demanding: “Where is the revenge for our martyred leader?”

Another shot lingered on a woman who had written a single word across her hand: “revenge”.

Mourners also carried the Iranian flag, portraits of the slain leader, the “clenched fist” emblem, and images of his son and successor, Ayatollah Mojtaba Khamenei – bidding farewell to the dead leader while pledging allegiance to the living one, with chants of “Labbaik ya Khamenei,” or “We are at your service.”

Whether Mojtaba Khamenei will appear at the funeral remains to be seen. He has not been seen in public since he was injured in the same strike that killed his father and other family members.

Caravans of mourners who have gathered nightly for more than four months since Khamenei’s death streamed into the courtyard.

Ayatollah Khamenei’s body was held for months, and the funeral is proceeding only now that a ceasefire has largely held, after Tehran and Washington signed a preliminary deal last month to end the fighting. Sporadic exchanges of fire have continued since.

A day earlier, at an official ceremony hosted by the heads of Iran’s three branches of government, delegations from about 100 countries paid their respects to the coffin – among them the Arab monarchies of Qatar, Oman and Saudi Arabia, whose attendance underscored the strange diplomacy of the moment.

Iran had fired missiles and drones at US bases in several Arab countries during the war, and struck Bahrain and Kuwait as recently as last week amid renewed tension over the Strait of Hormuz.

Saudi Arabia - which some reports say quietly aided the campaign against Iran during the war - was represented by Waleed Al-Khereiji, a deputy foreign minister.

As the Saudi delegation stood before the coffin, reciters read a Quranic passage recounting the Battle of Badr, in which a smaller Muslim force defeats a larger army of unbelievers; some regional commentators read the choice as a veiled message about where the kingdom stood.

Russia sent Dmitry Medvedev, the former Russian president.

Authorities have urged a mass turnout and forecast enormous crowds, with police estimates ranging as high as 20 million in Tehran and up to 35 million across events in Tehran, Qom, Mashhad and the Iraqi shrine cities.

By comparison, an estimated 10 million attended the 1989 funeral of the republic’s founder, Ayatollah Ruhollah Khomeini.

Mourners were sprayed with water as temperatures reached more than 30C and misting systems installed at the Mosalla lowered the temperature by about five degrees, the fire department said.

Many parked several miles away and walked because of traffic restrictions across the capital, while three metro stations near the site were temporarily reopened.

The public farewell is to continue until Sunday evening, when a funeral prayer will be held. The body will then be carried in procession through Tehran on Monday, followed by ceremonies in Qom on Tuesday, in Najaf and Karbala on Wednesday, and in Mashhad on Thursday, where Khamenei is to be buried at the shrine of Imam Reza.

Mojtaba Khamenei was named to succeed his father but has not appeared in public. Whether he will lead Sunday’s funeral prayer remains unclear.