Sir Keir Starmer warned that the government’s upcoming budget would be “painful” and called on the country to “accept short-term pain for long-term good”.

In a speech in Downing Street’s Rose Garden, the Prime Minister claimed that his government had achieved more in seven weeks than the Conservative government had done in seven years.

However, he warned that “things are worse than we ever imagined” with a £22 billion “black hole” in the public finances. Last week he reportedly discovered that the Tories had borrowed almost £5 billion more than the Office for Budget Responsibility had expected.

Sir Keir also claimed his government had inherited a “societal black hole” made worse by recent unrest, and said his decisions to release some prisoners early and make winter allowances for pensioners means-tested were “tough measures” needed to repair the country’s foundations.

He said: “There is a budget coming in October and it will be painful. Given the situation we are in, we have no other choice.”

“Those with the broadest shoulders should bear the heavier burden, and that is why we are cracking down on non-Dom citizens.

“Those who caused the mess should have to do their part to clean it up. That’s why we are strengthening the powers of the Water Regulator and supporting the imposition of heavy fines on the water companies that allow sewage to flood our rivers, lakes and seas.

“But just as I responded to the unrest, I must address the country and ask a lot of you too: to accept short-term pain for long-term good, the difficult compromise for a real solution.

“And I know that after everything you’ve been through, that’s a really big ask and a really hard thing to hear. That’s not the position we should be in. It’s not the position I want to be in, but we have to end the easy answer policy – that doesn’t solve anything.”

Asked what tax increases and spending decisions the government plans to announce on October 30, the Prime Minister said he would not “prejudge the budget” but reiterated his promise of “triple security for working people”.

“We were honest about the situation before the election and made it very clear what we would do with the tax increases,” he said.

“I have made it clear several times that social security contributions, VAT and income tax will not be increased, i.e. the triple lock for the working population, and this will continue to be adhered to.

“I also explained that our plans are fully funded and fully costed. What I did not anticipate was a £22 billion black hole.”

Sir Keir denied his comments were “performative”, adding: “I did not want to have to deal with the winter fuel allowance for pensioners… We need to fix the NHS, we need to fix our homes and schools and pensioners depend on them as much as anyone else. So I will not pre-empt the Budget but I will certainly not accept that the legacy we have is anything but terrible – a £22 billion black hole.”

In his speech, he called for the government to review prison capacity on a daily basis during the recent unrest to “ensure that we can arrest, charge and prosecute people quickly.”

“It’s a disgrace,” he said. “No prime minister should ever be in that position when trying to tackle unrest. That is our legacy and we will put it right.”

Asked about his government’s tax and spending plans, Sir Keir told reporters: “We have to get away from the idea that the only levers we can pull are tax increases or higher spending. Our primary mission is to grow the economy, to make sure we create money in the first place – that remains the primary mission, nothing can challenge that mission.”

“And that’s why it’s so important that we have a functioning transport system. That’s why it’s so important that we have a national health service that’s able to catch up. That’s why it’s so important that we have the Great British Energy national wealth fund, which we use to release the planning so that we can move forward.

“We made all of these decisions in the first seven weeks to make sure we get the economy where we need it to be, but we’re going to have to make difficult decisions.”

Conservative leadership candidate Kemi Badenoch, who serves as shadow minister for housing, said: “Keir Starmer thinks the British public are stupid, but his dishonest analysis is unconvincing. He made promises during the election campaign that he could not keep and now he is being exposed.”

Former minister Robert Jenrick, who is also a candidate for the Conservative leadership, accused Sir Keir of “shamelessly trying to rewrite history” and of “laying the foundations for huge tax increases”.

Outgoing Conservative Party leader Rishi Sunak wrote on X: “Today’s speech by Keir Starmer was the clearest indication yet of what Labour has always intended: to raise your taxes.”

Carla Denyer, co-leader of the Greens, said: “People did not vote to endure more economic suffering and misery. They were told they were voting for change, not for things to get worse before they get better.”

“Labour must be honest and say that if it were bolder and braver, it could choose to make things better for everyone.”