Kemi Badenoch tore into Sir Keir Starmer over the defence investment plan at Prime Minister’s Questions. The Tory leader insisted the £15billion plan to fund the military “does not add up”.

Speaking in the Commons, she said the armed forces needed £28billion more to defend the country. Mrs Badenoch said: “Three weeks ago, the defence secretary resigned, saying ‘I am being forced to make decisions that would increase the risk to personnel on operations and could make the country less safe’.

“Since that letter, the Prime Minister has only increased spending by 0.01%. We can count, the generals can count, the Kremlin can count. His plan does not add up. How can the Prime Minister possibly stand there and say that this is enough?”

But the Prime Minister defended the plan, saying it would take defence spending to £300billion over the next four years.

He insisted it had been welcomed by the Chief of Defence Staff, the First Sea Lord and the Chief of the Air Staff.

Sir Keir said: “All people who know what is in the plan, and welcome it. Contrast that with their record in government, because they hollowed out the armed forces.”

Mrs Badenoch also pressed him on whether Andy Burnham knew about the £5billion black hole in the plan.

She said the “plan has unravelled, it is a total dereliction of duty”, adding: “Did the member for Makerfield know that he was going to have to find £5billion for the Prime Minister’s plan?”

The PM replied: “We are in power with record investment in defence and security. I am proud of this Labour Government and any Labour prime minister would stand behind this plan.”

Mrs Badenoch then said: “It does not sound like he has told the member for Makerfield to find £5billion.”

She added: “The reason that he is in this mess is because he was too weak to cut welfare when he had the chance. There are only three ways to find the missing £5billion: increase borrowing, increase taxes, or cut welfare. Which one will he recommend to the member for Makerfield?”