Champion jockey Frankie Dettori has vowed to "rebuild his reputation" after accepting a six-month suspension, having been found guilty of using a banned substance.

Dettori, who will be 42 this month, tested positive in France on September 16 for a drug that has widely reported by British media to have been cocaine. He was cautioned by police for possession of the drug in 1993.

France Galop, the country's horse racing ruling body, announced on Wednesday that the Italian will be banned from November 20 to May 19, though it did not reveal the substance in question. It has asked other horse racing authorities around the world to enforce its decision.

"For similar cases, France Galop has never revealed the substances found and will therefore not reveal the substance for this specific case," spokesman Julien Pescatore said.

Dettori's legal representative Christopher Stewart-Moore said the jockey had accepted the punishment.

"He also accepts that he has let down the sport he loves and all those associated with it, as well as the wider public," Stewart-Moore said in a statement.

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

Dettori, who has five children with wife Catherine, is one of the world's most successful jockeys.

He is most famous for riding seven successive winners in one meeting at prestigious English course Ascot in 1996, and has more than 500 Group-level victories in his career so far.

He is a household name in Britain, where one bookmaker announced odds of his chances of success in next year's premier meetings immediately after the French authority's decision was announced.

Dettori revealed in October that he will be ending his fulltime role at the Godolphin stable next year, and last month news broke about his positive test during a race meeting at the Longchamps course in Paris.

"Racing has been good to Frankie and he knows that his privileged position brings with it responsibility," Stewart-Moore said.

"For this reason he is determined to rebuild his reputation when he returns to the saddle."

France Galop said Dettori will have to undergo further drug testing from April 20 before he is allowed to return to racing.

Stewart-Moore said the three-time British champion, who has admitted taking weight-loss drugs in the past, is taking full responsibility for the failed test.

"He is clear that the responsibility for his current situation lies squarely with him," Stewart-Moore said

"From the start of France Galop's inquiry he has acknowledged to them he has made a mistake and that the fault was his.

"Finally, he has asked me to thank everyone for the many messages of support he and his family have received."

The British Professional Jockeys' Association said it would support Dettori's rehabilitation, but denied there was a widespread problem of drug use among its members.

"From 2,607 in-competition urine tests and 3,697 breath tests since 2005, there is no evidence to suggest that there is a fundamental drug problem with jockeys," PJA chief executive Paul Struthers said.