Prime Minister Sir Keir Starmer earned a stern telling off from the Speaker of the House of Commons as he refused to give a clear answer about government plans to increase fuel duty. Conservative leader Kemi Badenoch asked about Chancellor Rachel Reeves’s announcement that the Treasury will begin increasing tax on petrol from September.

The Government will gradually reverse a 5p cut, which was introduced originally to help motorists cope with rising costs caused by the Ukraine law. She asked: “Can the Prime Minister tell us how a rise in fuel duty helps with the cost of living?” But Sir Keir insisted fuel duty was not rising – an apparent reference to the fact that it will not rise until September.

He also hinted that a U-turn may be coming, as he told MPs: “We will keep the situation under review in light of what’s happening in Iran.”

And the Prime Minister then repeatedly tried to turn the tables on Mrs Badenoch by insisting that she wanted the UK to join the US and Israeli strikes against Iran.

Sir Keir said: “If she were prime minister, we would be in the war and she would be coming back to Parliament a week later to say, 'oh sorry, we got that one wrong'.”

Commons Speaker Sir Lindsay Hoyle was forced to intervene. He stopped Sir Keir talking, and said: “I’m sorry I’m interrupting you, but unfortunately we’ve got to stick to Prime Minister’s Questions, not Opposition questions.”

Mrs Badenoch claimed that HMS Dragon would have left a week ago if she were the prime minister, while Sir Keir called for her to apologise for comments about the British armed forces.

Speaking at Prime Minister’s Questions, Sir Keir said: “In this job, you don’t get a second shot at making the right call on taking your country to war.

Mrs Badenoch replied: “If I were prime minister, HMS Dragon would have left a week ago. The only time he’s taken decisive action was stopping Andy Burnham from standing in the by-election.”

On HMS Dragon, Sir Keir said: “What’s been happening is it’s been carefully loaded with the anti-strike ammunition and capability that it needs. And the Navy and civilians have been working 22-hour shifts in relation to it.

“But in relation to those that are taking the action to defend us, what does she say? ‘Just hanging about’ – that’s how she described our pilots in the region.

“Let me tell you what they’ve been doing: flying sorties in seven of the 10 countries in the region, day and night, taking out incoming strikes, protecting the lives of others whilst risking their own.

“If she had any decency, she’d get up and she would apologise.”