Waiting time limits face being scrapped, with a record 5 million people left languishing on lists unless the NHS gets a cash boost, the head of the health service has said.

Simon Stevens called on ministers to honour Brexit pledges of a cash boost as he warned that funding levels are about to “nosedive”.

In a stark message to the Treasury, two weeks before the Budget, he said that NHS performance would decline significantly without an immediate cash injection, making the case for an extra £4bn next year.

Without extra funds, waiting times will rise to a record high of 5 million patients, with one in 10 people stuck on a waiting list by 2021, Mr Stevens said.

The deterioration would be so steep that Parliament would need to pass new laws, abolishing rights to treatment within 18 weeks, the NHS chief executive said.

Mr Stevens said the budget for next year will fall “well short of what is currently needed to properly look after our patients”.

"After seven years of understandable but unprecedented constraint, on the current budget outlook, the NHS can no longer do everything that is being asked of it,” he said.

An extra £4bn next year would only represent a return to the average rises seen in the six decades before 2010, he said. If increases are limited to 0.4 per cent next year - as is currently planned - it would mean deeper rationing of care, staff cuts and record waiting lists, he said.