Keir Starmer has paved the way for a new round of public spending cuts as bleak economic news blows a hole in Rachel Reeves’ budget.
The Prime Minister said the government would be “ruthless” as it sought to balance the books to avoid further tax rises.
This came as the cost of long-term government borrowing reached its highest level in 27 years on Monday morning, increasing pressure on the public purse.
At a press conference in London, Starmer repeatedly dodged questions about whether Chancellor Reeves would be forced to impose further cuts on Whitehall departments.
But the Prime Minister said the government would adhere to “fiscal rules” that rule out borrowing for daily spending and reduce debt.
“We put these fiscal rules in place very early today because we knew that the missing element in recent years was economic stability,” he said.
“We are determined to achieve this economic stability, which is why fiscal rules are a key element of what we do.”
Asked again whether spending cuts were on the cards, Starmer said: “We will be tough, as we have been tough in the decisions we have taken so far.
“We have clear financial rules, and we will adhere to those financial rules, which is why the Chancellor was absolutely right in the words she chose to describe the approach we will take.
Meanwhile, Starmer also insisted that Reeves has his full confidence as criticism of her performance as chancellor mounted.
“Rachel Reeves is doing a fantastic job, she has my full confidence and she has the full confidence of the whole party,” he said.
However, the Prime Minister dodged questions about whether Reeves would remain a chancellor at the next general election.