A senior Iranian official was quoted as saying by The Telegraph that most remaining scientists are no longer living at their homes or teaching at universities.
"They are either moved to safe houses in Tehran or to the north,” the official was quoted as saying. “Those who were teaching at universities are replaced with people who have no connection with the nuclear program.”
The newspaper said it was shown the names of more than 15 surviving researchers on a list of around 100 figures Israel says could face further targeting.
The relocations follow the execution this week of Roozbeh Vadi, a scientist hanged on Wednesday for allegedly providing information to Israel during the 12-day war in June.
Security arrangements for scientists have been overhauled since the June conflict, when the US struck Iranian nuclear sites with bunker-busting bombs and Tehran launched missiles at Israel, the report said.
Previously, a single Revolutionary Guards unit handled their security, but multiple agencies now share protective duties after some scientists said they no longer trusted their original guards, The Telegraph added citing an Iranian official.
'Dead men walking'
Israeli experts quoted by The Telegraph described the remaining personnel as “dead men walking” despite tightened security, including round-the-clock guards.
They said Iran’s nuclear program was designed with deputies for each key scientist, working in small teams to preserve capabilities in the event of an attack.
Danny Citrinowicz, former head of the Iranian strategic desk in Israeli Defense Intelligence, told The Telegraph that those who remain “will be at the forefront of any Iranian attempt to reach a nuclear bomb” and would “automatically become targets for Israel.”
Analysts believe some survivors have taken roles in the Organization of Defensive Innovation and Research (SPND), described by the US as “the direct successor organization to Iran’s pre-2004 nuclear weapons program.”
The figures had worked on adapting Shahab-3 missiles for nuclear warheads, making them “equally strategic targets” as those already killed, Ronen Solomon, an Israeli intelligence and defense analyst was quoted as saying.
Iran has long denied seeking nuclear weapons, citing a religious edict by Supreme Leader Ali Khamenei banning their use, and says its nuclear activities are entirely peaceful. Khamenei said last month that the West uses Tehran’s nuclear program as an excuse for confrontation.