Iran's supreme leader Ayatollah Ali Khamenei has called for the 'definitive punishment' of those behind the killing of its top nuclear scientist.

Tehran has blamed Israel for the assassination of Mohsen Fakhrizadeh, who is widely regarded as the driving force behind the country's nuclear programme.

In a statement, Khamenei said Iran's first priority was the "definitive punishment of the perpetrators and those who ordered it".

"We will respond to the assassination of Fakhrizadeh in a proper time. The Iranian nation is smarter than falling into the trap of the Zionists. They are thinking to create chaos," he added.

Earlier today, Major General Hossein Salam, the chief commander of the Islamic Revolution Guards Corps, termed the assassination as a "terrorist act designed and directed by Israel".

"The blind-hearted enemies of the Iranian nation, especially those who designed, perpetrated and supported this crime, should know that such crimes will not undermine the Iranians' will and determination to continue this glorious and powerful path, and that a severe revenge and punishment is put on the agenda."

Fakhrizadeh was targetted in Absard, a village just east of Tehran and is a retreat for the Iranian elite. 

Iranian state television said an old truck with explosives hidden under a load of wood blew up near a sedan carrying Fakhrizadeh.

As Fakhrizadeh's sedan stopped, at least five gunmen emerged and sprayed the car with bullets. Fakhrizadeh died at a hospital after doctors after paramedics failed to revive him.