London: A businessman has been arrested on suspicion of terrorism over an alleged attempt to import radioactive uranium into Britain.

The British citizen was detained by counter-terrorism police after the discovery of traces of substance at Heathrow airport soon after Christmas in a consignment of scrap metal intended for an Iranian-registered business based in the UK.

He was questioned under Section 9 of the Terrorism Act 2006, which created an offence “of making or possessing a radioactive device or possessing radioactive material with the intention of using it” in the commission or preparation of an act of terrorism. The section is very seldom used.

Police last night insisted they had found no evidence of a plot and said that the incident was not believed to be linked to any direct threat to the public.

The arrest of the man, who is in his 60s, could affect already heightened tensions between London and Tehran after the execution of a UK-Iranian dual national charged with spying for MI6.

The Iranian regime has also been accused by British intelligence services of being behind at least 10 plots to murder or kidnap opponents on UK streets in the last year and follows a crackdown in Iran on protests that followed the death in custody of a young woman who had refused to wear a headscarf.

The UK is expected in coming weeks to sanction the regime’s Islamic revolutionary Guard Corps, which is accused of sponsoring terrorist activity abroad.

The execution last week of Alireza Akbari, a former Iranian deputy defence minister with dual UK nationality, prompted the Foreign Secretary to summon Iran’s chargé d’affaires to register his “disgust”. Mr Akbari was charged with spying for MI6 amid claims he was tortured for 3,500 hours before being executed. Tehran’s military support for Russia in its war with Ukraine has further angered the West.