PARIS — Kazakh rider Dmitriy Fofonov has tested positive for a banned stimulant during the Tour de France.

The test result came to light Sunday minutes after Spain's Carlos Sastre won the race.

France's anti-doping agency says Fofonov used a heavy dose of the stimulant heptaminol. Agency head Pierre Bordry said the rider was asked whether he had a medical exemption, but Fofonov did not provide one.

The positive test came after the 18th stage Thursday.