An embarrassed BBC has backtracked on a "worldwide exclusive" featuring a man whose finger was "regrown" after being lost in an accident, following a backlash from scientists suggesting it was unlikely to be true.

Matthew Price, the BBC's New York correspondent claimed that scientists had used "pixie dust" to help Lee Spievak, from Ohio, regrow the tip of his finger which was lost in 2005 after being hit by the propeller of a model airplane at the toy shop where he worked.

In the story Price described Spievak's recovery as "a medical miracle" and "truly remarkable," and sets out how he sprinkled the wound with powdered "extra cellular matrix", a biological material derived from scraping the insides of pigs bladders. An accompanying BBC animation shows a finger regrowing two joints worth of skin and bone.

The story sounded like a medical and scientific breakthrough and was picked up by wire services, appearing in media outlets worldwide. What was omitted, however, was that the claims had not been substantiated by any kind of scientific publication, had not been subjected to peer review and that many of those featured in it had substantial commercial interests.

It has also emerged that exactly the same claims had been published in American media outlets in February 2007 - again featuring Lee Spievak.

The "pixie dust" described by Spievak, 69, was supplied by his brother, Alan, founder of Acell, a major biotech firm involved in the field of regenerative medicine. Dr Stephen Badylak, the University of Pittsburgh researcher cited by the BBC, is Acell's chief scientist.

Spievak went on to describe how the tip of the finger - including bone, tissue, skin and nail grew back.

"The second time I put it on I already could see growth. Each day it was up further. Finally it closed up and was a finger.

"It took about four weeks before it was sealed." Now he says he has "complete feeling, complete movement."

Such regrowth has, however, been the target of scientists worldwide for decades and would have been remarkable.

It would have been especially remarkable if it had been achieved using extra cellular matrix, which is a simple and common substance found throughout the body as a kind of scaffold to support new cell growth.

This, however, did not stop Acell from inviting TV crews into its labs and offering interviews with Badylak. He admitted he had no idea how the powder might work but suggested that Acell's powder might be able to enable regrowth of bones and tissue on a larger scale, perhaps even including entire limbs.

There were also suggestions the powder might be tested on a woman in Buenos Aires who has cancer of the oesophagus and that the US military was due to start trials of the powder to regrow parts of the fingers of injured soldiers.

The claim prompted widespread mockery from researchers questioning both the science and the need to target a woman in Buenos Aires for such a novel therapy. Some pointed out that the accompanying photos of Spievak's finger showed he had sliced off only the tip and that such injuries are renowned for self-healing.

The first sign of the BBC's discomfort came in an unusual item on Friday's edition of Radio 4's Today programme, when Ben Goldacre of the BadScience website was interviewed about the reporting of science and then effectively asked to rubbish the story.

On Friday Caroline Parkinson, one of the BBC's health correspondents, posted a story reporting on how specialists in regenerative medicine were "casting cold water over the claims". Her article was little more than a string of experts rebutting Price's original story.

Goldacre said later in comment posted on his website: "Price had wet himself with excitement at reporting on a new medical breakthrough on a scale with IVF. Any decent science or health correspondent would have known it was duff. "

A BBC spokesman said: "The BBC reported on the claims as they were made and as the sceptical views emerged, they were also reported as the story developed. This included a piece on Today with Ben Goldacre and an item on World Tonight."

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