Labour has accused Kemi Badenoch of scoring “cheap political points” after the Conservative party leader said Keir Starmer was “too scared” to join strikes on Iran.

Al Carns, the defence minister, said “serious politics” was required in response to Badenoch’s speech at the party’s spring conference where she criticised the prime minister’s stance on the US-Israel strikes on Iran a week ago.

Initially, Starmer did not allow the US to use UK RAF bases for the attack, and did not take part in initial military action against Iran, but then said the RAF would take part in defensive operations. A strike by an Iranian drone hit an aircraft hangar at RAF Akrotiri in Cyprus.

Badenoch told the Conservative’s spring conference in Harrogate, North Yorkshire: “At a time when Britain needs strong and decisive leadership, we have a prime minister who is too afraid of making the wrong decision, too afraid to make any decision at all.

“Last week’s byelection has spooked the Labour party. They watched the Greens campaigning on sectarian voting lines. A tactic Labour used for many years is now being turned against them. And now Keir Starmer is too scared to make foreign interventions for fear of upsetting a tiny section of that electorate.”

In response, Carns, a former Royal Marine, said: “Trying to score cheap political points off the back of a serious security situation is deeply irresponsible. This situation is above politics and requires calm collective decision making – not hyperbole and soundbites.

“British troops are doing an amazing job and no one should be questioning their commitment or competency. Serious times require serious politics, not political point-scoring on the back of our armed forces, civil service or [Ministry of Defence] personnel who are doing an amazing job.”

Badenoch said Starmer had equivocated when the US and Israel launched airstrikes on the Iran last weekend. The attacks killed Iran’s supreme leader, Ayatollah Ali Khamenei, as well as other senior figures.

In response, Iran attacked Israel and US allies in the Middle East, including Qatar and the United Arab Emirates, leading to an evacuation of British nationals.

The Iranian president, Masoud Pezeshkian, has since apologised to its Gulf neighbours and said it will no longer attack them – unless strikes on Iran are launched from their countries.

Badenoch denied she was calling for the UK to join the war uncritically, but hit out at apparent inaction from Starmer. She said: “Everyone remembers the mistakes of the Iraq war. Nobody sensible is suggesting that we should drop bombs without a second thought.

“But Keir Starmer spent days consulting lawyers, plucking up the courage to say whose side he was on. Canada and Australia have the moral clarity to do so immediately and unequivocally.

“And even now, our prime minister is sitting on the fence. We are in this war, whether Keir Starmer likes it or not.”

Badenoch, whose party finished fourth in the Gorton and Denton byelection and finds itself behind the Labour party and Reform UK in national polling, also said her party would rewrite the Mental Health Act so people who are considered a risk to the public are detained.

She referenced the case of Valdo Calocane, who killed three people in Nottingham in June 2023. “We are going to detain people who pose a risk to the public, keeping them safe, keeping the public safe. We cannot have dangerous men running around our towns and cities stabbing people.”

The Tory leader also said she would clamp down on antisocial behaviour, including the introduction of a new immediate justice community sentences for “low-level offences”. It would force criminals to undo damage at the scene rather than go through the courts. Badenoch named graffiti as one area that could fall into it.