LONDON (AP) — British officials say dogs trained to detect explosives are being deployed at airports to screen cargo for possible devices.

The Department of Transport said Sunday that each dog has been trained for 12 months to be able to detect small traces of explosives. They will be based in airport cargo sheds to screen large volumes of freight as one additional layer of protection.

Aviation minister Elizabeth Sugg says the use of the dogs "will bolster our existing rigorous security methods."

Dogs are already deployed at U.K. airports — including London's sprawling Heathrow Airport — to aid police in identifying criminals and preventing drug transport and other illegal activities.