John McDonnell has warned Rachel Reeves that any public spending cuts would be “politically suicidal” and risk tipping the UK into recession.
The former shadow chancellor said Labour should instead increase taxes on the wealthy.
Keir Starmer yesterday said the government will be “ruthless” in sticking to its fiscal rules as he repeatedly refused to rule out further spending cuts.
Treasury sources have also told HuffPost UK that the chancellor is determined to have an “iron grip” on the public finances.
Reeves finds herself under intense pressure as the value of the pound falls, government borrowing costs soar and inflation goes up.
On Radio 4′s Today programme this morning, McDonnell said any cuts to Whitehall budgets would be counter-productive.
He said: “There is obviously a problem. There is turbulence in the international markets and we’ve just got to see those through.
“The way you do that is you don’t turn to cuts. Not only would that be politically suicidal, it would undermine the political support upon which Labour got elected.
“In addition to that you would be taking demand out of the economy and you would be looking at, in doing that, turning a crisis into a recession.
“So I think you just need to see through the turbulence that is in the markets and in this instance we need to look to the Bank of England to intervene if necessary.”
McDonnell said Labour was wrong to rule out putting up income tax on the rich, or putting up corporation tax.
And he said Reform UK stood to benefit if cuts led to more voter disillusionment with the political process.
He added: “When we were preparing for government, we were looking to the bank of England to see us through the turbulence.
“There are two groups of people who make judgments on an incoming government. One is the international money markets, but the most important people are the electorate.
“I think what has to happen here is the electorate have to be protected, otherwise I’m afraid we’re looking at a level of disillusionment which then turns people towards Reform and I think that would be a disaster for the country.
“We have to look to what the response from the electorate would be to another round of cuts.”
McDonnell also warned that more cuts to the welfare budget, as Reeves is thought to be considering, would “force more into poverty and cause real hardship”.
He added: “When you’re in this situation, those with the broadest shoulders should carry the heaviest burden. I would look at increasing income tax on the wealthiest, but I would look at an honest discussion on how we tax wealth in our country.
“That way you can overcome these problems that we have in the markets because you’ll have a solid tax base.”