Kenyan Samuel Kalalei, who won the Athens Marathon last November, is the third athlete from the African nation to have been found in breach of anti-doping rules within 10 days.
The 24-year-old Kalalei has been provisionally suspended by the Athletics Integrity Unit (AIU) for testing positive for blood-booster EPO on June 4, the body said on its website.
Kalalei's failed test is the latest to tarnish the east African nation's reputation as the dominant force in global middle and long-distance running.
Sprinter Boniface Mweresa was last month dropped from the Kenyan team that topped the medal table at the African Senior Championships in Nigeria, after he failed a doping test.
Mweresa protested that he had taken declared supplements, but Anti-Doping Agency of Kenya (ADAK) said the substance found in his sample was prohibited.
The continental athletics showpiece ended on Sunday with Kenya winning 11 golds, six silvers and two bronze.
Former Commonwealth Games 10,000 metres champion and marathon runner Lucy Kabuu was on Saturday suspended by the AIU.
Kabuu, 34, tested positive for morphine during the Milan marathon which she won in April this year, two months after also triumphing in the Hong Kong event. The diminutive athlete won 10,000m gold and 5000m bronze at the 2006 Commonwealth Games in Melbourne.
"It's sad that we continue to lose top athletes to doping. Athletics Kenya obviously regrets the development and reiterates that athletes must run clean. Lucy (Kabuu) failed the test in Milan this year," Barnaba Korir, an AK Executive Committee member, said.
Asbel Kiprop, the former Olympic and three-time world 1500m champion, is serving a provisional suspension for testing positive for EPO. He denies the charge and his case will be heard by an International Association of Athletics Federation disciplinary tribunal this month.
Others serving provisional suspensions are former three-times Boston City marathon winner Rita Jeptoo and 2016 Rio Olympics marathon champion Jemima Sumgong.
