More than 40% of public-service spending was already on health, IFS research economist Max Warner said.

And to keep increasing the budget, other areas of government spending would have to be cut.

“Whichever party takes office after the next election, budgets for the next fiscal year and the choice of how much to give to the Department of Health and Social Care will effectively dominate everything else,” he said.

“Neither the Conservative Party nor Labour Party have been keen to set out spending plans.

“But the next government will have to confront this reality – and fast.”

‘Mounting demand’

Saffron Cordery, of NHS Providers, which represents NHS trusts, said the health service desperately needed extra funding.

“The NHS has been through its toughest financial year ever as budgets and services are stretched to the limit in the face of mounting demand and pressure,” she said.

“We can’t go on like this.”

Labour shadow health secretary Wes Streeting said: “Rishi Sunak has broken every promise he’s ever made on the NHS.

“It appears he has given up on turning the health service around.”