The secret phone system broken up by National Crime Agency

The National Crime Agency has penetrated a top secret communication system used by organised criminals.

Detective Sergeant John Cowell from the Metropolitan Police explained to the BBC's Tom Symonds how the Encrochat operating system is hidden and accessed on a seemingly normal smartphone.

The NCA has described the operation as the "biggest and most significant law enforcement operation carried out in the UK".

Read more: Hundreds arrested as crime comms system cracked