Iran's Supreme Leader Ayatollah Seyyed Ali Khamenei has vowed revenge and to continue the country's "scientific" activities after the killing of the country's chief nuclear scientist, as top Iranian officials pile blame on Israel over the killing.

Mohsen Fakhrizadeh, who became the face of Iran's controversial nuclear program, was killed in a district east of Tehran on Friday, in what Iranian officials are calling an assassination.

Iranian Defence Minister Brig. Gen. Amir Hatami said Fakhrizadeh was ambushed by gunmen and targeted by a Nissan vehicle explosion before a firefight ensued, semi-official news agency ISNA reported.

At a cabinet meeting Saturday, Iranian President Hassan Rouhani also said the country would retaliate and pointed to Israel for orchestrating the attack.

"The think tanks and the enemies of Iran must know that the Iranian nation and the officials in charge in the country are brave and determined to respond to the murder in time," he said.

He added that the killing was carried out at "the filthy hands of oppressors, in concert with the illegitimate Zionist regime.

In April 2018, Netanyahu mentioned Fakhrizadeh by name when he unveiled a nuclear archive that he said Israeli agents had smuggled out of Iran.

He called him the head of a secret nuclear project called Project Amad. "Remember that name, Fakhrizadeh," Netanyahu told reporters.

Fakhrizadeh is also mentioned in multiple reports by the US State Department and the International Atomic Energy Agency as holding deep insight into Iran's nuclear capabilities.