Jeremy Corbyn has said leaving the European Union will strip the United Kingdom of a health service that is free at the point of use.
The Labour leader gathered his entire shadow cabinet as well as union leaders in central-London to warn Labour voters not to back Brexit.
The intervention came after a pair of polls gave a six-point lead for the 'Leave' campaign.
Both phone and online Guardian/ICM surveys reported the same gap - up from 4% two weeks ago.
Leave now enjoys a 53%-47% advantage, once “don’t knows” are stripped out of the results, according to the research conducted over the weekend.
Corbyn said today: "A Vote to Leave is a vote to put our NHS in jeopardy, in the hands of those who want to break it up to end it as a service free at the point of use."
"Nigel Farage and Boris Johnson are wolves in sheep’s clothing, using their fake concern for the NHS to mask their real agenda."
He added: "Does anyone really believe that those from the hard right of the Tories and UKIP would spend any extra funds on the NHS? They’ve already promised this money again and again, on farming subsidies, fixing potholes and tax breaks no doubt for their rich friends and to corporations."
The Labour leader's warning echoes a recent attack on Boris Johnson and Michael Gove by Sir John Mayor.
The former Conservative prime minister and 'Remain' supporter, has said Gove wants to privatise the NHS and Johnson wants to charge for it. "The NHS is about as safe with them as a pet hamster would be with a hungry python," he told the BBC.
Speaking alongside Corbyn, TUC general secretary Frances O'Grady attacked Gove, Boris and others in the 'Leave' campaign as "fibbers, fake and phoneys".
"They love the NHS in a way that Dracula loves a blood ban," she added.
Shadow health secretary Heidi Alexander also insisted today "no one is more determined" to win the referendum for 'Remain' than Corbyn.
The Labour leader said on Friday he rated his enthusiasm for the EU at "7 to 7.5" out of 10.
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