Olympic marathon champion Jemima Sumgong has tested positive for the blood booster EPO in a test in Kenya, the IAAF revealed on Friday.

The 32-year-old became the first Kenyan woman to win Olympic gold in the marathon at last year's Games in Rio, is the reigning London Marathon champion, and was the points leader in the World Marathon Majors series.

"We can confirm that an anti-doping rule violation case concerning Jemima Sumgong (Kenya) has commenced this week," the IAAF said in a statement. "The athlete tested positive for EPO (Erythropoietin) following a no-notice test conducted in Kenya.

"This was part of an enhanced IAAF out-of-competition testing programme dedicated to elite marathon runners which is supported by the Abbott World Marathon Majors group."

Sumgong is now the highest-profile athlete out of more than 40 Kenyan track-and-field competitors to have failed doping tests since the 2012 Olympics in London.

She can request that her "B" sample, or backup sample, is also tested - if that is also positive for EPO, she faces at least a two-year ban.