Every Briton is being urged to stock up to nine litres of bottled water and three days’ worth of food in new government guidance designed to ensure that households can survive a weather, cyber or other serious emergency.

The Be Ready campaign is aimed at persuading people to stock up with supplies to last 72 hours, amid growing official concern about the impact of the climate crisis, technological dependency and hostile state threats.

Dan Jarvis, the security minister, said that “those who can follow this advice should follow this advice”. It amounted to “simple steps to be ready for everyday emergencies” as part of a wider, community-oriented effort “to improve our resilience as a nation”, he said.

Wes Streeting, the defence secretary, added that Britain also needed to prepare for the threat of “state-sponsored terrorism” by Russia or other hostile powers targeting everyday infrastructure.

“Terms like ‘hybrid warfare’ and ‘grey zone threats’ do not accurately capture or convey to the general public what…