The UK faces a greater risk of "electronic attack" than almost any other threat, according to a previously secret government assessment released today.
The Cabinet Office's National Risk Register ranks electronic attack on IT and communication systems as the second greatest risk, just behind attacks on the transport network.
The analysis examined a wide range of threats, including natural disasters and industrial accidents, and ranked them according to "relative likelihood" and "relative impact".
"There is a known risk to commercially valuable and confidential information in some government and private sector systems from a range of well-resourced and sophisticated attacks," said the report. "Electronic attack may be used more widely by different groups or individuals with various motives.
"IT systems in government departments and various organisations, including elements of the national infrastructure, have been and continue to be attacked to obtain the sensitive information they hold. Some of the attacks are well planned and executed."
Referring to the threat of terrorism, the document also said the UK remained at risk of attacks that "increasingly combine traditional intelligence methods with new and sophisticated technical attacks, for example by attempting to penetrate computer networks through the internet".
According to the government, organisations can prepare for electronic attacks by "avoiding reliance on a single technical solution [for example, not relying solely on mobile phones for critical communications] maintaining up-to-date contact details to ensure non-standard communication methods can be employed and focusing on identification and maintenance of critical users' access to communications where possible".
Organisations are advised to "consider which IT systems are needed to carry out critical activities, what information is needed to carry out critical activities, how this information is stored and how it is accessed, maintaining the same technology at different locations that will not be affected by the same disruption, and ensuring data is backed up and copies are kept securely off site".