"Accusing the Mujahedeen of killing the regime's nuclear experts is nothing new and is a reaction to the exposure of the entirety of the mullahs' nuclear structure and programme," the group said.

In Tehran, Rear-Admiral Ali Shamkhani, Iran's Supreme National Security Council secretary, charged Monday that the Mujahedeen were "certainly" involved, along with "the Zionist regime and the Mossad", referring to the Israeli government and its spy agency.

Fakhrizadeh was fatally wounded Friday outside the capital as assailants targeted his car and engaged in a gunfight with his bodyguards, according to the defence ministry.

The Mujahedeen, in a statement, dismissed "Shamkhani's rage, rancour, and lies" against the outlawed group, while claiming credit for past revelations on Iran's nuclear programme and previously secret sites.

"For the first time in 2004, the PMOI (People's Mujahedeen) identified Mohsen Fakhrizadeh as the official in charge of the regime's bomb-making apparatus," it said.

The group said it had "saved the world and the Iranian people from the danger of the mullahs' speedy access to a nuclear bomb and blocked their path".