UK underestimates threat of cyber-attacks from hostile states and gangs, says security chief

New head of National Cyber Security Centre to warn of risk to infrastructure in first major speech

• How Britain is preparing for cyberwar

The UK is underestimating the severity of the online threat it faces from hostile states and criminal gangs, the country's cybersecurity chief will warn.

Richard Horne, the head of GCHQ's National Cyber Security Centre, will cite a trebling of severe" incidents amid Russian aggression and recklessness" and China's highly sophisticated" digital operations.