Thousands of Iraqis have followed the coffin of Iranian military commander Qasem Soleimani, killed in a US air strike at Baghdad airport on Thursday.

Soleimani, viewed as a terrorist by the White House, was the architect of Iran's Middle East operations and Iran has vowed to take “severe revenge”.

The funeral procession which began in Baghdad on Saturday marks the beginning of days of mourning for Soleimani.

His body is due to be returned to Iran for burial in his home town.

Iranian President Hassan Rouhani has promised members of the dead commander’s family that Americans will “feel the impact” of their “criminal act... for years ahead”.

The crowds in Baghdad were also there to mourn the death of Abu Mahdi al-Muhandis, an Iraqi who commanded the Iranian-backed Kataib Hezbollah group and effectively led the Popular Mobilisation Forces (PMF) – an umbrella of militias in Iraq dominated by groups aligned with Iran.

Both Baghdad’s heavily fortified Green Zone, where the US embassy is located, and Balad air base north of the city came under rocket fire on Saturday but there were no immediate reports of casualties.

Mourners gathered in Baghdad in the early hours, waving Iraqi and militia flags and chanting “death to America”.

The funeral began at the city’s Al Muthana Airport, then moved to the gate of the Green Zone.

As the procession snaked through the streets, some mourners carried portraits of Soleimani while others held portraits of Iran’s Supreme Leader, Ayatollah Ali Khamenei.

Later, the procession left for the Shia Muslim holy cities of Karbala and Najaf.

Reports say the bodies of Soleimani and four other Iranians killed in the air strike will be flown on Saturday evening to Iran, which has declared three days of mourning for the assassinated general. His funeral in Iran is to be held on Tuesday.

Some Iraqis, conversely, celebrated in Baghdad’s streets at the news of Soleimani’s death. He was accused of orchestrating violent crackdowns on peaceful pro-democracy protests there in recent months. (BBC)