Shadow chancellor John McDonnell has said Labour will break away from a tax-and-spend approach to the economy.

He told BBC Radio 4's Today programme that the party was now "mainstream with commonsense policies".

But Mr McDonnell went on to insist that austerity was a political choice which Labour would not accept.

He said a Labour government would "invest in the long term in the economy" and "make sure that prosperity is shared by all".

The comments came a day after Mr McDonnellgave a speech setting out how Labour would control public spending through a "fiscal credibility" lock, under which day-to-day government spending would not exceed income.

Asked by Today whether this meant an end to tax-and-spend, Mr McDonnell replied: "It does really. We're going to break way from that old shibboleth.

"We're about managing the economy effectively, and actually that's what socialism is all about."

Responding to his remarks on Friday, the Conservative party said Labour had a history of spending and borrowing too much.

Some Labour figures said Mr McDonnell's policy was scarcely different from what the party had offered at the last election.

Mr McDonnell's latest comments come four days beforethe Budget, in which Chancellor George Osborne is widely expected to confirm the UK's economic performance has deteriorated in recent months and announce further spending cuts to reduce the deficit, forecast to be £73.5bn this year.

Commentators say Labour is under pressure to demonstrate it can be trusted on the economy after its election defeat, which was widely blamed on a failure to convince the public it had a plan to control public spending and borrowing, boost growth and raise living standards.

Mr McDonnell said under a Labour government borrowing would fund investment in new skills, infrastructure and technology.

Challenged over whether as chancellor he would be prepared to cut spending, Mr McDonnell said: "I will be absolutely ruthless about how we manage our spending... It's not about cutting, it's about making sure you spend the money wisely."