Ministers are preparing for a new pandemic that has the potential to kill 840,000 people after spreading through half the nation.
The worst-case scenario for a fatal epidemic spreading throughout the globe would leave approximately 1.3 million Britons in need of hospital treatment.
Experts predict that a respiratory disease will be the most likely next health emergency, but the government is still preparing for a variety of pandemic scenarios, including infections spread through blood or contact.
The information is given in the most recent risk record of the 89 major security threats to the United Kingdom.
Vladimir Putin’s ability to hold the world to “ransom” over energy supplies is included.
Deputy Prime Minister Oliver Dowden has declassified some information so the country can be “ready for anything”.
He published the register ahead of a visit to Hartlepool, where a new wind farm at Dogger Bank is being launched.
Some 277 turbines capable of powering up to six million homes will eventually be installed there.
Mr Dowden, who is running the country while Prime Minister Rishi Sunak is on holiday, said: “This is the most comprehensive risk assessment we’ve ever published, so that government and our partners can put robust plans in place.
“One of those rising risks is energy security.
“We’ve installed the first turbine at the future world’s largest offshore windfarm, which will provide secure, low-cost and clean energy for the British people, enabling us to stand up to Putin’s energy ransom.”
The list also includes the use of drones to disrupt the running of airports and attacks on undersea telecoms cables, as well as threats from terrorism, cyber attacks, rail disasters, environmental hazards and pandemics.
Matt Collins, Deputy National Security Advisor, said the report “offers even more detail on the potential scenarios, response and recovery options”.