Legendary jockey Frankie Dettori was suspended from riding worldwide for six months for what was termed a 'serious infraction of the doping rules' by French racing's governing body France Galop on Wednesday.

Crucially, though, Dettori's ban was backdated to November 20 - something he and his lawyer had been arguing for but which France Galop have never allowed before - which frees him up to ride in the Epsom Derby on June 1.

It means that the ban - which runs till May 19 - will see the 41-year-old Italian-born England based rider miss just the prestigious English Guineas meeting.

While there is no doubting he remains one of the greatest jockeys still riding he will still have to shrug off the cloud hanging over him following the failed dope test and convince trainers he is not battling a problem.

Dettori - probably racing's most high profile personality - tested positive for a non-performance enhancing banned substance at the September 16 Prix de l'Arc de Triomphe trials at Longchamp.

Dettori succeeded in getting back in time for the Derby because France Galop took into account his having agreed not to ride at all once his medical certificate had been withdrawn by the Medical Commission on November 20.

"Because Frankie Dettori said that he would not ride anywhere in the world from November 20 that has been taken into account," a France Galop spokesman told AFP.

"Thus the immediate ban is five months but it is six in counting the time since he voluntarily stepped down from riding on November 20."

Dettori, though, must return to France and undergo more medical tests before he is cleared to ride again after what France Galop termed in their decision was a 'serious infraction of the doping rules'.

"He must return to France and undergo biological tests on April 20. If they are clear then he is free to resume riding on May 19," the spokesman said.

France Galop said that they had demanded from their fellow global racing authorities to impose the ban as well.

Dettori's lawyer Christopher Stewart-Moore, who represented the jockey at both the Medical Commission and then the disciplinary hearing in Paris on Tuesday, issued a statement to the Press Association that Dettori was contrite and felt he had let the sport down.

"France Galop have today announced their finding that Frankie Dettori has committed a breach of their rules relating to prohibited substances," said Stewart-Moore.

"I have spoken to Frankie since the announcement was made and he has told me he fully accepts France Galop's decision.

"He also accepts that he has let down the sport he loves and all those associated with it, as well as the wider public.

"But most of all, and this is his greatest regret, he has let down his wife and children."

Although there has been much speculation as to the substance that he tested positive for it is unlikely, unless Dettori ever reveals, it will ever be known as France Galop policy is never to divulge such details.

He was one of five jockeys tested at Longchamp on September 16 but France Galop insist he was not targeted because of a tip-off.

Dettori, who had been tested six times in England this year, has had a year largely to forget.

Aside from the failed dope test, his hugely successful 18-year partnership with the Dubai-based Godolphin operation came to an acrimonious end in October.

Relations between the two parties had deteriorated during the season where he was increasingly playing second fiddle to French rider Mickael Barzalona.

The final straw appears not so much to have been the failed dope test but that he rode Camelot -- owned by Godolphin's bitter rivals Irish outfit Coolmore Stud -- in Europe's most prestigious race, the Prix de l'Arc de Triomphe in October.

Dettori originally secured his contract with Godolphin after losing out on a lucrative contract in Hong Kong when he received a police caution for possessing a small amount of cocaine in 1993 in London.

From that low he bounced back in September 1996 when he experienced his most eyecatching performance by winning all seven races on the card at Ascot.

He has also won over 100 Group One races, including an Epsom Derby and also three Arcs.