Touring broadcast studios this morning, Technology minister Chris Bryant denied the review will mark a return to austerity.

But he acknowledged some parts of the budget will be ‘more stretched’.

He told Times Radio: ‘That period of austerity where I think previous governments simply cut all public service budgets just because they believed that was what you had to do is over.

‘But, secondly, we are investing, but it’s not just about spending money, you have to get return, and that means we have to have change and we have to have a plan for change in every single one of our public services.’

He pointed to increased investment in defence and health, but added: ‘There are going to be other parts of the budget that are going to be much more stretched and be difficult.’

Ms Reeves will have some £113billion to distribute that has been freed up by looser borrowing rules on capital investment.

But she has acknowledged that she has been forced to turn down requests for funding for projects she would have wanted to back in a sign of the behind-the-scenes wrangling over her spending review.

Economists have warned the Chancellor faces unavoidably tough choices in allocating funding for the next three years.

She will need to balance manifesto commitments with more recent pledges, such as a hike in defence spending, as well as her strict fiscal rules which include a promise to match day-to-day spending with revenues.

The expected increase to police budgets comes after two senior policing figures publicly warned that the service is ‘broken’ and forces are left with no choice but to cut staff to save money.

Nick Smart, the president of the Police Superintendents’ Association, and Tiff Lynch, acting national chairman for the Police Federation of England and Wales, said policing was in ‘crisis’.

In a joint article for the Telegraph, they said: ‘Police forces across the country are being forced to shed officers and staff to deliver savings. These are not administrative cuts.

‘They go to the core of policing’s ability to deliver a quality service: fewer officers on the beat, longer wait times for victims, and less available officers when crisis hits.’

The Department of Health is set to be the biggest winner in Ms Reeves’ spending review on Wednesday, with the NHS expected to receive a boost of up to £30billion at the expense of other public services.

Meanwhile, day-to-day funding for schools is expected to increase by £4.5billion by 2028-9 compared with the 2025-6 core budget, which was published in the spring statement.

Elsewhere, the Government has committed to spend 2.5 per cent of gross domestic product on defence from April 2027, with a goal of increasing that to 3 per cent over the next parliament – a timetable which could stretch to 2034.

Ms Reeves’ plans will also include an £86billion package for science and technology research and development.