The NHS would suffer from an "economic shock" that would impact the UK if it leaves the European Union, Health Secretary Jeremy Hunt has warned, sparking a furious backlash from pro-Brexit Conservatives.

In the latest instalment of the increasingly bitter civil war within the Tory party over the issue, Mr Hunt's comments were dismissed as "absurd and demeaning" by a former Cabinet colleague.

Writing in the Observer newspaper, Mr Hunt, a close ally of David Cameron, said several recent studies had shown that Britain's GDP would fall by five per cent by 2020, as a result of leaving the 28-nation bloc.

"This would inevitably mean less money for public services like the NHS. Those who want to leave need to explain how they could protect the NHS from this economic shock," he said.

"Another issue is the damage caused by losing some of the 100,000 skilled EU workers who work in our health and social care system. Uncertainties around visas and residency permits could cause some to return home, with an unpredictable impact on hard-pressed frontline services."

Mr Hunt said the NHS was "one of the reasons why people are proud to be British. It provides outstanding care to more than a million of us every day, despite huge pressure caused by tight finances and an ageing population," he said.

"At the last election, the British people were clear – a strong NHS needs a strong economy. So those who back Brexit need to explain what that would mean for the NHS."

However former Defence Secretary Liam Fox was among the Conservatives who hit back at Mr Hunt. "How many more colleagues will be forced into absurd and demeaning scare stories? Very sad," he told The Daily Telegraph.

Another Tory MP, Stewart Jackson, said: "Jeremy Hunt has to explain how uncontrolled EU migration and Turkish EU accession will help an overstretched NHS on his watch and afterwards."

And Matthew Elliott, chief executive of Vote Leave, said: "Does this government's scaremongering know no bounds? Under Jeremy Hunt's stewardship, the NHS has plummeted into a financial crisis. If we vote to leave we can stop wasting money on EU bureaucrats and instead spend our money on our priorities like the NHS."

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