TEHRAN : Giant portraits of Ayatollah Ali Khamenei, Iran's late supreme leader killed in US-Israeli airstrikes, hung from Tehran's Grand Mosalla on Tuesday as workers raced to prepare for his grand funeral ceremony.

His funeral, initially delayed at the height of the Middle East war, will take place as Iran and the United States observe a fragile ceasefire after signing a preliminary deal to halt the conflict.

Khamenei, a spiritual figure for many Shias, was killed aged 86 at his compound in the centre of the Iranian capital on February 28, the first day of the war.

His public funeral will begin on Saturday, with his body lying in state at the colossal complex in central Tehran that hosts major Friday prayers, official ceremonies and religious gatherings.

The bodies of his slain relatives will also be presented.

The ceremonies are expected to draw between 15 and 20 million mourners, according to officials, which would make it the biggest state funeral in the country's history.

Workers applied fresh paint across the venue, while a heavy police presence could be seen around the site.

Footage aired by state television showed workers welding metal structures as cranes lifted construction materials around the complex.

With huge crowds expected, state television has been urging mourners to use public transport to reach the venue and issued public safety messages urging people to stay hydrated, as temperatures are set to rise during the funeral period.

An AFP journalist saw some lanes on major roads across the capital already closed, adding to Tehran's notoriously heavy traffic.

State television has also devoted much of its programming in recent days to documentaries on Khamenei's life.

'Bright future' -

A separate event for foreign heads of state is scheduled for Friday, according to Ali-Akbar Pourjamshidian, secretary of the funeral ceremony headquarters.

He estimated that representatives from around 30 countries are expected to attend the funeral with people pouring in from neighbouring countries, including Iraq, Afghanistan and Pakistan.

Foreign ministry spokesman Esmaeil Baqaei, speaking on state television, said "we have not extended an official invitation to Europe".

He accused European nations of standing "on the wrong side of history" and called their position on the US-Israeli war "truly disgraceful".

Iran has meanwhile maintained its close ties with its ally Russia throughout the war.

Tehran, as well as the holy cities of Qom and Mashhad, which will host later stages of the funeral and burial ceremonies, will observe public holidays while the events are underway.

Authorities have ordered public and private offices in Tehran to close from Saturday through Monday, while major traffic restrictions will make much of the city centre inaccessible to private vehicles.

The ceremony also comes six months after nationwide protests that began over the rising cost of living before evolving into anti-government demonstrations.

Across Tehran, funeral posters promised Iran a "bright future", while others displayed the ceremony's slogan: "We Must Rise".

Following the ceremonies in Tehran, Khamenei's body will be taken to the holy Iraqi cities of Najaf and Karbala before his burial on July 9 at the shrine of Imam Reza in the northeastern city of Mashhad, his birthplace.

But at the main ceremony in Tehran, it remains unknown if Khamenei's son and successor Mojtaba, who has not been seen in public since his appointment, will be present.

"The issue of the Supreme Leader's attendance is not within my authority or knowledge," said Pourjamshidian.

"If there is any programme, it will certainly be announced by the Office of the Leader of the Islamic Revolution."