More than half of Britons support raising National Insurance contributions so the extra revenue could be invested in the NHS, a survey has indicated.

YouGov research shows 53 per cent of people supported the idea of a 1p-in-the-pound rise in National Insurance, from 12 to 13 per cent, if it was used to fund healthcare, while 26 per cent opposed it—down from 37 per cent in 2014.

It comes after Simon Stevens, the NHS England chief executive, told MPs the health service "got less than we asked for" in funding, directly contradicting Prime Minister Theresa May amid a nationwide crisis in accident and emergency departments.

Funding has been "back-ended" to end the of the decade and will actually fall in real terms in the 2018-19 financial year, he said. Ms May said on Monday that Mr Stevens' five-year forward plan "would require £8bn of extra spending, we've actually put £10bn of extra spending in".

Mr Stevens told the public accounts committee: "Like probably every part of the public service we got less than we asked for in that process.

"So 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."

YouGov also reported that 42 per cent of people supported raising the basic income tax rate from 20 to 21 per cent to support the NHS, while 37 per cent opposed the idea. On both income tax and National Insurance, 21 per cent were undecided.

The pollsters said: "While more popular, increasing National Insurance instead of income tax could end up hitting poorer people harder.

"This is because even the lowest earners pay National Insurance, but the £11,000 tax-free allowance would mean increasing income tax would affect them less.

"Additionally, an income tax increase would see better-off pensioners contributing as well, which they would not do under a National Insurance increase."

The National Insurance hike was most popular among the over-60s and Liberal Democrat supporters, while people aged 18 to 39 were less enthusiastic.

Support for maintaining NHS spending at its current level sits at less than a third, YouGov found — down to 31 per cent from 44 per cent in April 2014.

Overcrowding in NHS hospitals has become so severe that last week more than 20 trusts issued ‘black alerts’, meaning they are unable to guarantee life-saving emergency care.

The top-level alert, considered a “serious incident” by NHS England, can result in scheduled operations being cancelled and patients being diverted to other hospitals as overflowing A&E departments struggle to cope.