David Cameron faced fresh political embarrassment last night as a second Conservative MEP came forward to attack the NHS. The Tory leader had tried to limit the damage inflicted on the party by Daniel Hannan, who told a US news channel that he would not "wish the NHS on anybody". Mr Cameron described Mr Hannan as "eccentric", adding that the NHS was his party's "number one priority".

But yesterday, as the debate over the NHS moved to this side of the Atlantic, one of Mr Hannan's Conservative colleagues in the European parliament inflamed the controversy by expressing support for his position.

Roger Helmer told the BBC: "Now we all love the NHS, but I think we all know in our hearts that it is no longer the envy of the world. If the Americans came to me and said, 'Would you recommend us taking up a system just like the British NHS?', I think I would have to say 'No'."

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Labour has been quick to capitalise on Mr Cameron's discomfort, claiming the row exposed "deep ambivalence" within his party towards the health service. But Mr Cameron said: "The Conservative Party stands four square behind the NHS. We are the party of the NHS, we back it, we are going to expand it. It is our number one mission to improve it. [Mr Hannan] does have some quite eccentric views about some things ,and political parties always include some people who don't toe the party line on one issue or another issue."

But in an extraordinary day of political jousting, ministers and Labour big hitters were soon queuing to argue that Mr Hannan had revealed that the NHS was not safe in the hands of the Tories. Lord Mandelson said the public would "find it shocking that a Conservative parliamentarian should go to the US to slag off the NHS". He added: "What we see is the two faces of the Conservative Party." Andy Burnham, the Health Secretary, said Mr Hannan's remarks represented the Tory leader's "worst nightmare".

"What has happened within the past 48 hours is what Cameron has feared most because it lays bare the Tories' deep ambivalence towards the NHS," he said. "Their election strategy is not to talk about the NHS. Cameron knows there is deep hostility towards it within his ranks. Hannan is not the only one; many senior Tory MPs would privately agree with his comments."

Mr Burnham's attack earned a quick repost from the shadow health secretary, Andrew Lansley, who accused him of deliberately "misleading the British public". Former deputy prime minister John Prescott called on Mr Cameron to take further action against Mr Hannan.

The Tories were then hit with more apparent disunity, after another MEP, Roger Helmer, said that Mr Hannan had done the party "a service" by raising the matter of NHS reform. The damage inflicted on his party is a great frustration to Mr Cameron, who has been extremely wary of being accused of not giving the NHS his full support. He has even pledged to protect its budget at the cost of cutting more heavily in other departments across Whitehall.

Timothy Kirkhope, the leader of the Conservatives in Europe, said of Mr Hannan: "In a foreign country, you should be doubly careful about what you say. You don't want to give the wrong impression of the party's policy to the Americans."

Mr Hannan, who became the new darling of the Tory grassroots after his attack on Gordon Brown became an internet sensation in March, had criticised the NHS while appearing on the conservative US news channel Fox News. He told friendshe did not want to inflame the situation any further by speaking out.