Tablets and smartphone devices have been banned from meetings of the Cabinet over fears that foreign spies could turn them into 'bugs' without ministers' knowledge.
UK security services are worried that foreign states including China, Russia, Iran and Pakistan have developed the ability to infect gadgets with a Trojan virus, allowing the perpetrators to control the devices and monitor conversations, even when turned off.
It has been reported that iPads used by Francis Maude, the Cabinet Office minister, were removed from the room before a presentation could begin, and ministers were told not to touch them beforehand.
In response to the threat, those working in sensitive Government departments have been handed lead-lined soundproof boxes, into which they have been told to put phones and tablets when discussing delicate matters, the Telegraph reported.
Security officials are also concerned by reports that souvenir USB sticks handed to delegates at the G20 summit in St Petersburg may have contained a virus. It is feared the drives may enable Russia's intelligence agency to hack UK Government computers.
The vast majority of those who enter Number 10 are told to hand in their smartphones to security staff, and only get them back when they leave.
Earlier this week, William Hague revealed that his phone has been secured by GCHQ to protect against bugging.
The Foreign Secretary said: "I think my phone has been modified by GCHQ enough that it'd be difficult, but I'm sure the Chinese have had a good go."