Heathrow Airport

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By Daniel SandfordBBC News Home Affairs correspondent

Police are investigating after metal contaminated with uranium was found at London's Heathrow Airport last month.

Officers of the Metropolitan Police 's Counter Terrorism Command responded to the security alert which was triggered on 29 December .

, Said the uranium came from Pakistan.

One line of inquiry is whether it was the result of " poor handling" in the country, The Bbc was told. Police say there was no threat to The Public .

It was found in a shipment of Scrap Metal , a source Said .

Alarms were triggered at Heathrow after specialist scanners detected the substance as it was ferried to a freight shed owned by handling firm Swissport, The Sun Said .

The Shipment 's intended destination is not clear. No-one has been arrested.

The Metropolitan Police 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. "

Commander Richard Smith from The Force 's counter terrorism team separately told The Bbc : " 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. "

Strict protocols must be followed in order to fly Dangerous Cargo , including uranium, being loaded onto The Base of units in the cargo hold and ensuring a minimum distance is kept between the nuclear material and cabin above.

Uranium is an element which occurs naturally. It can have nuclear-related uses once it has been refined, or enriched. This is achieved by the use of centrifuges - Machines which spin at supersonic speeds.

Low-enriched uranium can be used to produce fuel for commercial Nuclear Power plants.

Highly enriched uranium has a purity of 20% or More and is used in research reactors. Weapons-grade uranium is 90% enriched or More .

Source of news: bbc.com