Revolutionary Guards chief Hossein Salami praised Firouzabadi's "continuous efforts" to defend "the sacred system of the Islamic Republic of Iran", in a statement published on the Guards' Sepahnews website.

A trained doctor, Firouzabadi joined the Basij Islamic volunteer militia during the Iran-Iraq war of 1980-88.

Serving in administrative roles, he swiftly rose up its ranks before being named head of the armed forces in September 1989 by Iran's supreme leader Ayatollah Ali Khamenei, remaining in the post until 2016.

Iran's armed forces chief has authority over both the regular army and the Islamic Revolutionary Guard Corps.

That made Firouzabadi one of the main architects of Iranian military support for Baghdad and Damascus in their battles against the Islamic State group and other jihadist movements.

Replaced by Mohammad Hossein Bagheri at the head of the armed forces, Firouzabadi then served as Khamenei's military adviser until his death.

The Fars news agency reported that he died after contracting Covid-19.

In 2018, during an international face-off over the death in jail of Iranian-Canadian environmentalist Kavous Seyed Emami, Firouzabadi accused Western countries of using lizards and chameleons as "nuclear spies" to "find uranium mines and atomic activity" in Iran.