The massive number of mourners in the hometown of the slain commander of the Revolutionary Guards' foreign arm appeared to match the huge turnout seen in the cities of Tehran, Qom, Mashhad and Ahvaz.

They converged from afar on Azadi Square where two flag-draped coffins were on display, with the second one reportedly containing the remains of Soleimani's closest aide, Brigadier General Hossein Pourjafari.

"We're here today to pay respects to the great commander of the holy defence," said one of the mourners who came from the southern city of Shiraz to attend the funeral in Kerman.

"Haj Qasem was not only loved in Kerman, or Iran, but also the whole world," Hemmat Dehghan told AFP.

"The security of the whole world, Muslims, Shiites, Iraq, Syria, Afghanistan and especially Iran, all owe it to him," said the 56-year-old war veteran.

Soleimani was killed outside Baghdad airport Friday in a drone strike ordered by US President Donald Trump, ratcheting up tensions with arch-enemy Iran which has vowed "severe revenge".

The assassination of the 62-year-old heightened international concern about a new war in the volatile, oil-rich Middle East and rattled financial markets.

Iraq's parliament has demanded the government expel the 5,200 American troops stationed in the country in response to the drone attack which also killed top Iraqi military figure Abu Mahdi al-Muhandis.

NATO chief Jens Stoltenberg warned on Monday that Iran must avoid "further violence and provocations" after the alliance held emergency talks on the crisis.

The European Union, whose foreign ministers will hold emergency talks on the crisis Friday, said it was in both Iran and Iraq's interests to "take the path of sobriety and not the path of escalation".

Saudi Arabia -- an oil-rich US ally seen as vulnerable to Iranian counter strikes -- also appealed for calm after a "very dangerous" escalation.

Soleimani is expected to be buried at the martyrs' cemetery between 2:00 and 4:00 pm (1030 to 1230 GMT).