The UK has failed to prepare for war in a “whole-nation endeavour”, two former defence ministers have warned.

Outgoing armed forces minister James Heappey revealed that only Ministry of Defence (MoD) officials turned up to an exercise to prepare for wartime scenarios which was meant for the whole of Government.

He called on ministers to do more to prepare for conflict just weeks after resigning his MoD post.

Ben Wallace, the Conservative former defence secretary, agreed with his colleague, and said too many in Government were “just hoping everything will go away”.

Writing in the Telegraph newspaper, Mr Heappey said the UK was behind allies who had taken steps to reinforce citizens’ preparedness for war.

He gave the example of Sweden, where the government has handed out a booklet explaining what to do in a time of war, including which emergency food provisions to store.

Mr Heappey wrote: “It’s a stark reminder that war is a whole-nation endeavour and, to be frank, in the UK we’re a very long way behind.”

The former soldier, who resigned as a minister at the end of March, said ministers across the Government needed to explain how Britain would feed itself during a war, and how public services would work.

The Conservative MP said not enough figures within Government were considering these preparations.

He pointed to a “whole of Government exercise” which Mr Wallace had “pushed hard for” while serving as defence secretary, aimed at getting ministers and officials into a war bunker to see what their working environment would be.

“In the end, rather depressingly, it was just defence ministers, senior military officers and MoD officials that participated,” Mr Heappey wrote.

Mr Wallace told the Telegraph: “The growing instability and insecurity directed at Britain and her allies means that the whole of society needs to make a step change towards recognising that our core duty is to think about our defence and our resilience.

“It’s how we used to think during the Cold War, and everyone from local government to the MoD played their part.”

While Mr Wallace claimed the MoD had made such a change, he added “there are too many people in Government and society relying on just hoping everything will go away”.

The intervention from the two long-serving defence ministers came as Rishi Sunak faces pressure to increase defence spending.

Conservative MPs have urged the Prime Minister to raise this to 2.5% of gross domestic product (GDP).

Jens Stoltenberg, the head of Nato, meanwhile warned that the West’s enemies are becoming increasingly aligned.

In an interview for the BBC’s Sunday With Laura Kuenssberg, the alliance chief warned of growing links between Russia, China, Iran and North Korea.

A Government spokesman told the Telegraph an extra £24 billion would invested in the armed forces between 2020 and 2025, which he described as the largest sustained investment since the Cold War.

He added: “The UK has robust plans in place for a range of potential emergencies and scenarios, with plans and supporting arrangements developed, refined and tested over many years.”

The Government has launched a national resilience framework aimed at equipping citizens with more information about how to survive in crisis scenarios.

At the end of 2023, Deputy Prime Minister Oliver Dowden suggested people should stock up on candles, first aid kits and battery-powered torches and radios to prepare themselves.