Iran is unlikely to retaliate over the assassination of a prominent nuclear scientist before the inauguration of Joe Biden in case it jeopardises any future sanctions relief, the top US envoy on Iran told Reuters on Thursday.

Mohsen Fakhrizadeh, who had little public profile in Iran but had been named by Israel as a prime player in what it says is Iran’s nuclear weapons quest, was killed on Friday when he was ambushed on a highway near Tehran and his car sprayed with bullets.