At the entrance to the vast religious complex where Ayatollah Ali Khamenei’s body is set to lie in state from Saturday, dozens were hard at work under an intense heatwave to prepare for the assassinated supreme leader’s grand funeral.

Security was on high alert ahead of the start of the funerary activities for Iran’s ruler for three decades, with dozens of personnel stationed at the main entrance to the Grand Mosalla, methodically stopping each car in the vicinity.

Passengers must present a special permit to enter the premises, which have yet to be opened to the public.

AFP obtained special access on Thursday, as a handful of curious bystanders watched the preparations from just outside the complex.

Within, the walls were draped in massive portraits of the late Khamenei, alongside black flags of mourning and red ones symbolising martyrdom and vengeance.

In one image, Khamenei — then the president — appears alongside young fighters in the Iran-Iraq war of the 1980s.

Hossein Moghadassi, one of those who has been working on the site for days, said, “We are planting flowers and watering the shrubs for the farewell ceremony of our martyred guide.”

He was clad in a hat and a scarf to cover his face as temperatures soared, with trucks transporting hundreds of boxes of drinking water in anticipation of the mercury surpassing 35º Celsius on Saturday, the first of six days of national mourning.

“People will come from all over Iran. There will be huge crowds,” Moghadassi added.

‘Vengeance’

Authorities expect between 15 and 20 million people to participate in the funeral in Tehran alone. The gates to the Grand Mosalla are set to open at 6am (0230 GMT) on Saturday.

Within the premises, dozens of ambulances and rescue vehicles have been parked in preparation for the funeral of the supreme leader, who was killed in US-Israeli strikes on February 28.

Black banners bear several of Khamenei’s most famous quotes, while an image of the late leader with a raised fist — a symbol of resistance against the West — was ubiquitous across the site.

Other banners read: “We are mourning, but we remain on our feet.”

The Mosalla’s main building, a mosque, will host the supreme leader’s remains over three days for “pilgrims”, according to the organisers.

On Monday, a procession will travel through the streets of the capital before arriving on Tuesday in the Shia holy city of Qom.

Khamenei will be buried on July 9 in Mashhad in northeastern Iran, another holy city and the late ruler’s birthplace.

Iran’s top negotiator in talks with the US, Mohammad Bagher Ghalibaf, on Thursday called for a massive turnout as a way to avenge Khamenei’s death.

“I invite all the Iranian people… to write a glorious page in the history of Islamic Iran through your presence,” said Ghalibaf, who is also Iran’s parliament speaker. “The nation’s call for vengeance must ring in the ears of the whole world.”