His proposals will include a national security council on which security, intelligence, and military chiefs could sit as well as senior ministers and top civil servants, Whitehall officials said yesterday.
A national security document, due to be published on Wednesday, will warn that threats to Britain go beyond that of terrorism fuelled by extreme Islamism. It says they include those posed by climate change, increasing competition for natural resources, migration, and potential pandemics.
It is also expected to warn of new weapons, such as cyber attacks, already in the hands of hostile powers and potentially in those of terrorist groups.
It may not be long before al-Qaida-inspired groups - well aware of the potential impact of disrupting global and national computer networks - will be involved in cyber warfare, officials and independent analysts say.
Brown first mooted his proposal for a national security strategy shortly after he became prime minister last summer. The task of drawing it up was given to Sir Gus O'Donnell, the cabinet secretary. It was due to be published before the end of last year and has been postponed more than once since.
Officials were divided about how broad they should paint the security threats facing Britain, and whether they should include such issues as social cohesion, for example. One issue is how far the military should have a bigger role not only in combating threats abroad, but working with the security and intelligence agencies at home. Traditionally, the armed forces have been deployed strictly at the request of civilian authorities - to deal with floods, or foot and mouth - and military chiefs have wanted it that way.
A national security council is not expected to take the place of the Cobra system, named after the cabinet office briefing room in Whitehall where it meets.
