Samuel Kalalei, who won the Athens marathon last year, is the third Kenyan athlete to have been found in breach of anti-doping rules in the last 10 days, Reuters news agency reports.

Kalalei, 24, tested positive for the blood-boosting substance EPO and has now been provisionally suspended by the Athletics Integrity Unit (AIU).

He follows sprinter Boniface Mweresa, who was dropped last month from Kenya's team at the African Senior Championships in Asaba, Nigeria, after testing positive for a prohibited substance which he had claimed was a legal supplement, says the Anti-Doping Agency of Kenya.

While on Saturday, former Commonwealth Games 10,000-metre champion and marathon runner Lucy Kabuu was suspended by the AIU for failing a doping test. Kabuu, 34, tested positive for morphine during the Milan marathon which she won in April, two months after her victory in the Hong Kong event.

"It's sad that we continue to lose top athletes to doping," a spokesperson for the organisation told Reuters.

"Athletics Kenya obviously regrets the development and reiterates that athletes must run clean."