DUBAI (Reuters) - Hundreds of thousands of mourners, many chanting, beating their chests and wailing in grief, turned out across Iran on Sunday to mourn slain military commander Qassem Soleimani, who was killed in Iraq in a U.S. military strike.

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Soleimani’s body was returned home on Sunday - given a hero’s welcome as it arrived in the southwestern city of Ahvaz and then flown to the holy Shi’ite Muslim city of Mashhad.

State television showed huge crowds of mourners turning out to pay their respects, their chants, chest-beating and wails in keeping with the style of mourning common among Shi’ite Muslims.

Mourners carried posters bearing Soleimani’s image as his casket wrapped in the national flag was driven slowly through the crowds.

Soleimani, the architect of Tehran’s overseas clandestine and military operations as head of the Revolutionary Guards’ Quds Force, was killed on Friday in a U.S. drone strike on his convoy at Baghdad airport.

While many Iranians have rallied in to show grief over the death of Soleimani, regarded as the country’s second most powerful figure after Supreme Leader Ayatollah Ali Khamenei, others worry his death might push the country to war with a superpower.

On Friday, Khamenei promised harsh revenge. U.S. President Donald Trump on Saturday threatened to hit 52 Iranian sites “very hard” if Iran attacks Americans or U.S. assets.

When Soleimani’s body arrived home, IRIB news agency posted a video clip of the casket wrapped in the national flag being unloaded from a plane as a military band played.

Thousands of mourners dressed in black marched through the streets of Ahvaz beating their chests, state television showed.

The body of Iranian-backed Iraqi militia leader Abu Mahdi al-Muhandis, who was killed in the attack with Soleimani, was also flown to Ahvaz, according to IRIB.

Soleimani’s body will be taken to Tehran on Monday and then he will be buried at his hometown Kerman on Tuesday.

Tens of thousands of people marched in Iraq on Saturday to mourn Soleimani and al-Muhandis, chanting “Death to America”.