The Kenyan-born athlete could now face a two-year ban from competitive running after traces of the banned substance were found in his A-sample at the race, which he won in 2 hours 12min 28sec, in the Turkish city on November 17.

French sports newspaper L'Équipe has claimed Kiprotich was already a figure of suspicion after he raced in the Daegu Marathon - which he won in a personal-best time of 2:08:33 - "when he was under suspension of 15 days following administrative failures relating to the medical surveillance of high-level athletes" in April.

Kiprotich, 28, began his athletics career as a steeplechaser but progressed to marathon running after he started winning road races in France.

He was selected to compete at the London 2012 Olympics, but failed to complete the marathon.

His B-sample will now be analysed.

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