Dressed in black and draped in the red, white and green flags of the Islamic Republic of Iran, mourners held up portraits of Khamenei and his son and successor Mojtaba
In a show of public devotion to the Islamic Republic's theocratic state and revolutionary zeal, Iran is staging a week of mass funeral processions for the supreme leader killed in February by the opening airstrikes of the war.
After a day lying in state indoors for senior Iranian leaders and foreign officials to visit, Khamenei's coffin was put on display under glass outdoors, along with those of his daughter, son-in-law, daughter-in-law and 14-month-old granddaughter.
There has still been no public sighting or image released of his son, the new leader, said to have been injured in the same attack.
Mourners filed into the vast courtyard of the Imam Khomeini Grand Mosalla, beating their chests, wailing and waving the banners of the Islamic Republic.
Women dressed in black chadors wore white visors or held umbrellas to shield from the hot mid-morning sun.
"Let us wail!" a compere encouraged the crowds through a loudspeaker.
Chants of "Death to America" echoed through the huge prayer hall.
"Everyone here has come to avenge the blood of their supreme leader," Arash Rahimi, 40, told Reuters in the crowd.
"As our leader has said, we have a blood feud with the United States. Our relations with the United States will never be good."
The funeral is taking place at a critical moment for Iran, with its clerical rulers, backed by the military, buoyed from having survived the onslaught with their ruling system intact.
The war has been paused for a ceasefire under an agreement with the United States that Iran's authorities say will ultimately bring huge economic benefits, in line with what they describe as a victory over a superpower.
The Axios news website quoted US President Donald Trump as saying peace talks had been paused for a week for the events surrounding the funeral.
With Iran's leaders all attending, the US could take them all out with "one shot" it quoted Trump as saying: "But we are not going to do that because then we would have nobody to negotiate with."
Trump also told the news outlet that he was surprised to see some Iranians crying at the funeral, saying he thought people hated Khamenei.
"Maybe it's fake tears," he said.
Iran's embassy in Armenia reacted to Trump's remarks in a post on X: "You don't understand these things because you have neither civilisation, nor history, nor honour."
Within Iran, beyond the displays of solidarity with the leadership, it remains impossible to assess how deeply public loyalty runs across a country of 90 million people.
Weeks before the war, hundreds of thousands of Iranians demonstrated against the government in protests that were put down in a violent crackdown in which thousands were killed.
But there has been little or no public sign of such dissent since the US and Israeli attacks began.
During the war, more than 3000 people were killed including many of Iran's most senior politicians and military commanders.
Military bases and major infrastructure projects were destroyed causing billions of dollars in damage.
But Iran successfully struck US bases in the region, inflicted pain on the Gulf Arab countries that host them, and asserted its control of the Strait of Hormuz, causing a spike in global energy prices which Trump said led him to push faster for peace.
The interim deal reached last month includes the unfreezing of billions of dollars in Iranian assets held abroad, and waivers from financial sanctions that had brought Iran's economy to its knees.
