Dr. Dukan, a former GP whose diet regime has gained both success and notoriety in the last decade, was last week given an eight-day ban from practicing medicine by France’s national medical board, his lawyer told French daily Le Figaro on Monday.

The board found Dukan guilty of a “breach of ethical regulations” after he prescribed Mediator, a diet pill linked to hundreds of deaths, on five separate occasions, and then lied about it.

“In resorting to untruthful assertions, Dr. Dukan demonstrated behaviour which lacked probity and discredits the profession,” said the medical board in its ruling.

Dukan, 72, was also ordered to pay €6,000 in damages to a former patient who developed heart problems in the early 1970s to whom he prescribed Mediator, even though the drug was only intended to treat diabetes.

Mediator has been at the centre of a major medical scandal in France since it was pulled off the market in 2009 after evidence emerged that it had caused hundreds of deaths due to damage to heart valves.

Jacques Servier, the now 90-year-old founder of the Servier bio-pharmaceutical company which produced the drug, is currently on trial in Nanterres, France, for “aggravated fraud.”

Mediator was never authorized in the UK or US.

The Dukan diet, launched in 2000 in France, has had significant global success since being translated into English in recent years, and was reportedly the diet of choice of the Duchess of Cambridge, Kate Middleton in the run-up to her wedding to Prince William in 2011.

The diet, however, has also attracted widespread criticism from medical experts. In November 2012, the British Dietetic Association ranked the Dukan diet number one in its list of “The Five Worst Celebrity Diets to Avoid,” saying “There is little solid science behind this.”

“This diet is so confusing, time consuming, very rigid and, in our opinion, so very hard to sustain,” the BDA added. 

This is not the first time Dukan has landed in trouble with medical authorities in France. In 2012 France's College of Physicians lodged a complaint against him after it accused him of breaching the ethics code when he suggested schoolchildren's grades should be bumped up if they manage to maintain a healthy weight.

The idea was included in a book brought out by Dukan in January last year.

At the book's launch he said: “There is nothing unhealthy about educating youngsters about nutrition.

“My idea would change nothing for those who have no need to get thinner. But for those who do, it would only motivate them to lose weight.”