According to the law enforcement agency, the package was found during a routine search carried out on Dec 29, 2022.
British tabloid newspaper The Sun reported that the package had originated in Pakistan, before it got on a flight from Oman.
As per BBC, investigators were looking into whether the highly-sensitive substance, found in a shipment of scrap metal, made its way to the flight as a result of "poor handling" in Pakistan.
Meanwhile, Richard Smith, a police official told the media, "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."
"Although our investigation remains ongoing, from our inquiries so far, it does not appear to be linked to any direct threat," he maintained.
Reuters reports that uranium can be used for civilian power generation and scientific purposes and is a key ingredient in nuclear weapons. Certain isotopes emit radiation that can be harmful to humans, and the metal itself is toxic if ingested or inhaled.