Rudy Giuliani, the front-runner for the 2008 Republican nomination, was accused last night of smearing the NHS to attack Democratic plans for universal healthcare in America.

Mr Giuliani launched a radio advertising campaign saying that the proposals from Democrats such as Hillary Clinton smacked of European-style socialism that would lower standards in the US.

“I had prostate cancer five, six years ago,” the former New York mayor said. “My chance of surviving prostate cancer – and, thank God, I was cured of it – in the United States? 82 per cent. My chance of surviving prostate cancer in England? Only 44 per cent under socialised medicine.”

His advert prompted Alan Johnson, the Health Secretary, to make a rare intervention into US politics as he pleaded with Mr Giuliani to stop kicking the NHS. Mr Johnson told The Times: “The British NHS should not become a political football in American presidential politics. Our rate of prostate cancer survival is actually much higher than has been claimed. The latest data shows a survival rate of over 70 per cent – and increasing.”

The Office for National Statistics says that the five-year survival rate from prostate cancer in Britain is 74.4 per cent.

Mr Giuliani’s campaign did not give an immediate response. But a spokeswoman has previously insisted that he would continue to repeat the statistic and run the advertisement. She said the 44 per cent figure came from an article in a “highly respected intellectual journal” published by the right-wing Manhattan Institute, which he had read because “he is an intellectually engaged human being”.

The article’s author, David Gratzer, who is an adviser to Mr Giuliani’s campaign, has acknowledged to The New York Times that the statistic is seven years old and “crude”.

He said that it came from the Commonwealth Fund, which specialises in health policy issues. But the same organisation has since issued a statement accusing Dr Gratzer of misusing its research.

Mr Johnson himself cited a report this year from the Commonwealth Fund that placed Britain’s health system top of a league table of six nations including Australia, Canada, Germany, New Zealand and the United States.

“While neither health system is perfect, the recent Commonwealth Fund report placed the UK system at the top of its analysis and the US at the bottom,” Mr Johnson said.

US health experts also disputed both the accuracy of Mr Giuliani’s figures and questioned whether it was fair to make a direct comparison.

Doctors in the two countries have different philosophies for treating the disease, with the US putting more emphasis on early diagnosis and surgery. An analysis of mortality rates suggests that about 25 out of 100,000 men are dying from prostate cancer each year in both Britain and the US.

Brantley Thrasher, at the University of Kansas Department of Urology, told The Washington Post that it was “impossible to say” whether a prostate cancer patient has a better chance of surviving under a “capitalistic” or “socialistic” medical system.

Ian Thompson, of the University of Texas, said: “Certainly, if you intensively screen for prostate cancer, you will find early disease. And simply because you find it earlier, you will always have longer survival after the disease is diagnosed.”

The issue of healthcare will be a key battleground in the presidential campaign. Democratic candidates, including Mrs Clinton, have set out plans to extend coverage to the tens of millions of citizens without health insurance.

The Organisation for Economic Cooperation and Development recently issued a report giving warning that the US faces soaring budget deficits unless it does more to control spending on health, which far exceeds that of even the richest European countries, even though 47 million Americans – including nine million children – have no cover.

At the same time Sicko, the latest documentary from the left-wing film-maker Michael Moore has provoked anger from Republicans by painting a flattering portrait of healthcare in Canada, Britain and France, as well as Cuba – which he contrasts with the alleged failures of the US system. Moore said of the NHS: “It doesn’t mean it doesn’t have flaws but it’s a hell of a lot better than what we have.”

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