An Iranian opposition news site on Wednesday identified Sa'id Borji as the man tasked by Tehran to built nuclear warheads and the fission chain reaction needed for the production of a nuclear device.
Saudi-backed UK-based Iran International news said Borji had worked under Mohsen Fakhrizadeh, head of the republic's nuclear program who was assassinated in an attack attributed to Israel in 2021.
He also held a senior position in SPND, a government linked research institute, believed to be involved in Project Amad, Iran's military nuclear program.
The news site said Borgi had worked at the Parchin nuclear site east of Tehran with Russian nuclear scientists to experiment in explosive cells connected to nuclear weapons. In 2011, he had been part of another project tied to the nuclear program at Ahmadabad, believed to be the Abada nuclear site.
The Iranian finance ministry revealed in 2019 that Borji was an explosives and metals expert working with a subsidiary of SPND, which develops bombs and missiles.
He has been on the U.S. Iranian sanction list since 2019.
Meanwhile Iranian negotiators departed to Vienna on Wednesday, where talks on a possible return to the 2015 nuclear deal were to resume after being suspended for months.
"Bagheri Kani will leave Tehran in a few hours ... In this round of talks, which will be held as usual with the coordination of the European Union, ideas presented by different sides will be discussed," Foreign Ministry spokesperson Nasser Kanaani was quoted in local media to have said.
"Iran is determined to reach a stable agreement that guarantees the rights and interests of the Iranian nation," Kanaani said, calling on Washington to "provide the conditions for the effective progress of the talks by taking the necessary decisions".