The picture shows Servants of the Imam Reza Shrine carrying the coffin of Iran's assassinated top nuclear scientist Mohsen Fakhrizadeh during his funeral procession in the northeastern city of Mashhad, Iran on Sunday. Photo: AFP

Iran was on Monday laying to rest one of its top nuclear scientists, as the Islamic republic weighed how and when to retaliate for an assassination pinned on arch-foe Israel.

The killing of Mohsen Fakhrizadeh - whom Israel has dubbed the "father" of Iran's nuclear weapons program - has once more heightened tensions between Tehran and its foes, with President Hassan Rouhani accusing the Jewish state of acting as Washington's "mercenary."

Fakhrizadeh died on Friday after being seriously wounded when assailants targeted his car and engaged in a gunfight with his bodyguards outside Tehran, according to Iran's defense ministry.

The funeral got underway with a religious singer alluding to the martyrdom of Imam Hossein, a revered seventh century holy figure from whom Shiite Muslims draw inspiration.

A large display showed a picture of the slain scientist next to Iran's supreme leader Ayatollah Ali Khamenei, as well as former top general Qasem Soleimani, who was killed by the US in a drone strike in Baghdad in early 2020.

Iran's parliament on Sunday demanded a halt to international inspections of nuclear sites in the country, signalling another potential retreat from a key commitment in its 2015 nuclear deal with world powers, while a top official hinted Iran should leave the global non-proliferation treaty.

The Supreme National Security Council of Iran usually deals with decisions related to the country's nuclear program, and parliamentary bills must be approved by the powerful Guardians Council.

President Rouhani has stressed his country will seek its revenge for the assassination in "due time" and not be rushed into a "trap," with less than two months to go before US President Donald Trump leaves office after four hawkish years at the White House.

AFP