Kazakhstan’s Dmitri Fofonov has tested positive for a banned stimulant, his Credit Agricole team said on the final day of the Tour de France.

The 31-year-old, who learned of his positive test after finishing 19th overall in the race on Sunday, explained to his team he bought a product over the internet to fight cramps. He has been suspended and is now facing the sack.

“He has failed to respect our basic team rules,” Credit Agricole manager Roger Legeay told AFP. “No products can be taken by any riders unless they have prior authorisation from the team doctor. “He has made a mistake, which can happen, but it’s not good news for us or for him.”

Fofonov is the fourth rider from the Tour to have tested positive for a banned substance.

Italian Riccardo Ricco, and Spanish duo Manuel Beltran and Moises Duenas all tested positive for the banned blood booster EPO (erythropoietin) and were thrown out of the race.

The 31-year-old Fofonov, from Almaty, turned professional in 1998. Since 2000 he has competed with only French teams, picking up just three wins: the national time trial title (2000), a stage on the Tour of Catalonia (2002) and a stage on the Dauphine Libere earlier this year.