Hundreds of thousands of mourners accompany Qassem Soleimani's body for funeral procession

Protesters in Tehran demonstrate over the US airstrike in Iraq that killed Iranian Revolutionary Guard General Qassem Soleimani i Credit: Ebrahim Noroozi/AP

Hundreds of thousands flooded streets in Iran on Sunday to walk alongside the casket carrying the remains Qassem Soleimani, a top Iranian general killed in a US airstrike in Baghdad,

Mourners beat their chests and wept, carrying posters bearing the image of the leader of Iran's expeditionary Quds Force that organises Tehran's proxy forces in the Middle East.

The leader of one such proxy, Lebanon's Hezbollah, said Soleimani's killing made US military bases, warships and service members spread across the region fair targets for attacks.

Meanwhile, Iraq's parliament voted in favour of a resolution calling for an end of the foreign military presence, an effort aimed at expelling the 5,000 US troops stationed in Iraq over the war against so-called Islamic State.

One Iranian official suggested the US airstrike would see Tehran break further out of its unraveling nuclear deal with world powers.

Soleimani's body was carried through the city of Mashhad as part of a grand funeral procession across the Islamic Republic.

Throngs of mourners carried the flag-draped coffin of Soleimani off a plane in Ahvaz in southwestern Iran earlier on Sunday, as tensions escalate between the US and Iran.

It came as President Donald Trump threatened to bomb 52 sites in the Islamic Republic "very fast and very hard" if Tehran retaliates by attacking Americans.

The 52 sites represent 52 American hostages taken by Iran many years ago, but Mr Trump did not identity the targets but said "some [are] at a very high level & important to Iran & the Iranian culture."

The 1954 Hague Convention, of which the US is a party, bars any military from "direct hostilities against cultural property."

However, such sites can be targeted if they have been re-purposed and turned into a legitimate "military objective," according to the International Committee of the Red Cross.

Gen Soleimani died in an air strike at Iraq’s Baghdad International Airport on Friday, in an attack ordered by Mr Trump.

Flag draped coffins of Gen. Qassem Soleimani and his comrades are carried through Ahvaz, Iran. Credit: AP

After thousands mourned Soleimani and others killed in the strike in Baghdad on Saturday, authorities flew the general's body to the southwestern Iranian city of Ahvaz on Sunday, according to the state-run IRNA news agency.

An honour guard stood by early Sunday as mourners carried the flag-draped coffins of Soleimani and other Guard members off the tarmac.

The caskets moved through the street, carried on a truck, with mourners wearing black, beating their chests and carrying posters with Soleimani's portrait.

Demonstrators also carried red Shiite flags, which traditionally both symbolize the spilled blood of someone unjustly killed and call for their deaths to avenged.

The killing of Soleimani has escalated tensions between the US and Iran and Tehran has vowed to avenge the killing.

The tensions take root in Mr Trump pulling out of Iran’s nuclear deal with world powers.

Iranians across all political lines were shocked by the death of a commander, widely seen as a pillar of the Islamic Republic, at a moment when it is beset by US sanctions and recent anti-government protests.

Retaliation could potentially come through the proxy forces Soleimani oversaw as the head of an elite unit within the paramilitary Revolutionary Guard.

Soleimani's longtime deputy Esmail Ghaani already has taken over as the Quds Force's commander.

Mourners carry the coffin of Iran's top general in Karbala, Iraq. Credit: AP

Iran has promised harsh revenge and on Saturday, a series of rockets exploded in Baghdad.

They fell inside or near the Green Zone, which houses government offices and foreign embassies, including the U.S. Embassy.

Officials brought Soleimani's body to Ahvaz, a city that was a focus of fighting during the bloody, 1980-88 war between Iraq and Iran in which the general slowly grew to prominence.

After that war, Soleimani joined the Guard's newly formed Quds, or Jersualem, Force, an expeditionary force that works with Iranian proxy forces in countries like Iraq, Lebanon and Yemen.

Authorities also plan to take Soleimani's body to Mashhad later Sunday, as well as Tehran and Qom on Monday for public mourning processions, then onto his hometown of Kerman for burial Tuesday.

This marks the first time Iran honored a single man with a multi-city ceremony.

Not even the Islamic Republic's founder, Ayatollah Ruhollah Khomeini, received such a processional with his death in 1989.

Soleimani on Monday will lie in state at Tehran's famed Musalla mosque as the revolutionary leader did before him.