The head of the National Health Service (NHS) has hit back, accusing Theresa May of "stretching the truth" after the prime minister said the service received more money than it had asked for.

It follows a week of mounting chaos in the NHS, particularly in accident and emergency units, where four-hour patient waiting times were routinely missed.

As a result, growing pressure was placed on the prime minister as health officials and MPs called on May to step in and provide extra funding.

Instead however, May refused to accept the calls – rejecting the British Red Cross' warning that the service was facing a "humanitarian crisis".

Speaking on Sky News on Sunday (8 January), the Conservative prime minister said: "I do not accept the description that the Red Cross has made of this.

"Yes there are huge pressures, but I think first of all we should thank all those dedicated professionals in the NHS who've been working so hard over what is always is a difficult period in terms of the number of people using the NHS.

"We had, I think, it was something like 150,000 medical professionals working in the NHS on Christmas Day and New Year's Day, and I want to say thank you to them for the work that they're doing.

"Yes, there are significant pressures, but we recognise those pressures. We asked the NHS a while back to set out what it needed over the next five years in terms of its plan for the future and the funding it would need. They did that, we gave them that funding and, in fact, we gave them more funding than they required.

"Funding is now at record levels for the NHS. More money has been going in."

May repeated the claim during Prime Minister's Questions on Wednesday (11 January). However, in a separate hearing, Simon Stevens, chief executive of NHS England, rejected the comments.

Appearing at a Public Accounts Committee hearing on the financial stability of the NHS, Stevens said: "I think it would be stretching it to say the NHS has got more than it asked for. There are clearly very substantial pressures, and I don't think it helps anybody to try and pretend that there aren't."

He added: "We are spending 30% less per person than Germans are."

The Shadow Health Secretary pounced on the comments and urged the prime minister to listen to experts such as Stevens. "Theresa May needs to come out of her bunker, admit she's got it wrong and guarantee the funding the NHS needs," said Jonathan Ashworth.

"Number 10 should listen to the experts like Simon Stevens and not be briefing against him," he added.