Mohsen Fakhrizadeh was killed when his car was ambushed on a highway outside Tehran in November 2020, in an attack Iran blamed on its regional arch-foe Israel.

The nine defendants were charged with "corruption on earth" and collusion with Israel, both capital offences in the Islamic republic, judiciary spokesman Massoud Setayeshi said.

"Fakhrizadeh's case has 15 defendants," Setayeshi told a news conference.

Along with those facing the death penalty, a further six people had "other accusations" levelled against them, he said.

In September, Tehran's chief prosecutor Ali Salehi had announced 14 people were indicted in the case.

The charges against them included "colluding with the purpose of disrupting national security" and "actions against national security", Salehi said at the time.

Fakhrizadeh had been under US sanctions for his role in Iran's nuclear programme when he was killed.

Iranian authorities claimed the attack included a bombing and a remote-controlled machine gun.

Israel has never commented on the killing.

In 2018, the Israeli government accused Fakhrizadeh of leading Iran's efforts to build an atomic bomb, a claim Iran has always vehemently denied.