An o2 shop is boarded up after being looted in last week's riots in London.

An o2 shop is boarded up after being looted in last week's riots in London.

THE UK’S SECURITY service MI5, and the Government Communications Headquarters (GCHQ) – the national communications interception centre – have been tasked with decrypting data sent between the mobile handsets of people involved in last week’s rioting.

The Guardian reports that the two agencies – whose anti-terrorism work is normally of a grander international scale – have been called in to help decrypt data sent across networks including that of the BlackBerry Messenger, the encrypted messaging forum.

The latter method of sending data had been considered a key method of spreading details about the riots, as it is not only encrypted but also closed to the general public – with users only able to send messages to others who have already shared their contact details.

The decision to involve MI5 illustrates the gravity with which the UK government is treating the riots, as MI5 usually focusses on issues of broader national security while police are tasked with the maintenance of public order.

David Cameron last week told the House of Commons that his government was working with police and intelligence services to check if it would be “right” to block access to social networks in some circumstances.