Border Force officials found small amount on passenger flight from Oman on 29 December.
Counter-terrorism police have launched an investigation after Border Force officials seized material containing uranium at Heathrow.
Scotland Yard confirmed its counter-terrorism team was investigating after the contaminated material was discovered as part of a routine security screening.
It was discovered on 29 December on a passenger flight that arrived from Oman, according to the Sun. It is understood the package originated from Pakistan and was destined for an Iranian business with premises in the UK.
“I want to reassure the public that the amount of contaminated material was extremely small and has been assessed by experts as posing no threat to the public,” said Commander Richard Smith of the Met.
“Although our investigation remains ongoing, from our inquiries so far it does not appear to be linked to any direct threat. As the public would expect, however, we will continue to follow up on all available lines of inquiry to ensure this is definitely the case.”
Uranium is a natural metal that exists in the earth but can be dangerous to humans because it is a radioactive element.
The Met said it had not made any arrests and is working with partner agencies to investigate and ensure there is no risk to the public.
“However, it does highlight the excellent capability we and our partners have in place to monitor our ports and borders in order to keep the public safe from any potential threats to their safety and security that might be coming into the UK,” Smith said.
A Met spokesperson said: “We can confirm officers from the Met’s counter-terrorism command were contacted by Border Force colleagues at Heathrow after a very small amount of contaminated material was identified after routine screening within a package incoming to the UK on 29 December 2022.”
It is understood that the Home Office does not believe there is any threat to the public.
A Home Office spokesperson said: “We do not comment on live investigations.”