South Dorset MP Richard Drax is among Conservative backbenchers calling for an increase in defence spending.

Prime Minister Rishi Sunak would not commit to ramp up defence spending ahead of the next general election, as Tory MPs - including Dorset's Richard Drax -  pressured him to invest more amid increasing global threats.

Sir Julian Lewis, who chairs Parliament’s intelligence and security committee,  urged the Prime Minister to increase the UK’s defence spending commitment to 2.5% of gross domestic product (GDP)

Mr Sunak said the Government would meet the target “when circumstances allow”, and suggested it would set out a roadmap to the commitment as part of the next spending review in 2025, now likely to fall after a general election.

Over the weekend, Foreign Secretary Lord Cameron warned that the world faces a period of heightened peril, claiming the “lights are absolutely flashing red” on the global dashboard following the US-UK airstrikes against Houthi rebels in response to their attacks on merchant ships passing through the Red Sea.

Sir Julian told the Commons: “The Prime Minister was clearly absolutely justified to respond as he did, particularly after the direct attack against HMS Diamond.

“But given that at the time of the Falklands campaign, we had 35 frigates and destroyers and were spending 4.5% of GDP on defence, whereas both those figures can be cut in half to describe our situation today, does he agree with me that we certainly should not be reducing the numbers of frigates or destroyers and we certainly should not be mothballing or otherwise decommissioning our amphibious assault ships?”

Newspaper reports have recently suggested the Royal Navy could mothball two assault ships, HMS Albion and HMS Bulwark, in order to free up seamen to serve on other vessels.

The Prime Minister replied: “I’m happy to reassure him that our intention is to increase defence spending from where it currently is up to 2.5% when circumstances allow.”

Mr Drax,  meanwhile suggested Mr Sunak should go further than the 2.5% target.

He said: “While it is important how we spend defence money, it is vital and without doubt that defence needs a lot more money, more than 2.5% and these arbitrary targets, if our brave men and women are going to fight a sustained conflict in the years ahead.”

Mr Sunak said the Ministry of Defence had received “a £24 billion cash increase” at the last spending review, “the largest sustained increase since the end of the Cold War”.

He added: “Since then we have invested an extra £5 billion in increasing stockpiles and improving the sustainability of our defence nuclear enterprise, and in 2025 when we have the next spending review we will, of course, set out the target and the path towards 2.5%.”

Defence Secretary Grant Shapps warned in a major speech on Monday that the UK is facing a “pre-war world” and the “peace dividend” that allowed successive governments to ease spending on defence is over.

His words have been viewed as a push for extra funding – both at home and by Nato allies, many of whom are not meeting the alliance’s 2% of GDP spending target.