A pandemic flu bug would pose a greater threat to Britain than terrorism or floods, a new report has said.
Until now, the official list of threats and risks facing Britain has been kept confidential, although MI5 has for some time published on its website the terrorist threat level, currently defined as severe.
Plans to publish a risk register were announced by the Prime Minister in March during a statement to the Commons on national security strategy. Top of the list is pandemic flu because of the conviction in Whitehall that it is "not a question of if but when" and that it could kill 750,000 people, reports The Telegraph.
The Cabinet Office risk-register report does not include a top-ten list of threats, as this was deemed unhelpful in trying to inform people of the kind of threats facing Britain.
The risk register places the threats in context, spelling out how they are likely to affect people's way of life.
On terrorism, according to Whitehall sources, the report will focus on the likelihood of attacks on "transport and in crowded places" and will highlight the growth in terrorist activities in Britain in the past four years.
MI5 is tracking some 2,000 individuals regarded as terrorist suspects. The figure was 500 in 2004, rising to 800 by 2005 and 1,600 by the end of 2006. There are known to be 30 plots being investigated by MI5 and the police, and those convicted since 2000 came from the North, the Midlands and the Home Counties as well as London.
Experts cannot predict when it will happen but say when it does it will come in several waves of three to six months over a two-year period.