Wednesday 26 August 2015 17:28, UK
The IAAF has announced that Kenyan athletes Koki Manunga and Joyce Zakary have returned positive doping tests at the World Championships in Beijing.
The pair, who have accepted provisional suspensions, were targeted in pre-competition tests at their team hotel on August 20 and 21.
Zakary was second in her opening 400 metres heat on Monday, running a national record of 50.71 seconds.
But the 29-year-old did not run in the semi-finals a day later despite having the eighth best qualifying time.
Manunga, 21, ran in the opening heats of the women's 400m hurdles on Sunday and finished sixth of seven, failing to reach the semi-finals.
An IAAF statement said: "These targeted tests were conducted by the IAAF at the athlete hotels during the pre-competition phase. The IAAF will not discuss the details of the cases as they progress through the results management process."
The positive tests will take the shine off what has been an impressive championships for Kenya so far - they topped the medal table after the opening four days with nine medals, including four golds.
Athletics in Kenya has come under close scrutiny following a spate of positive tests from their athletes over the past few years and the nation's athletics governing body has opened an investigation into these fresh cases.
"Athletics Kenya (AK) has already met with the IAAF and the athletes involved, and has begun investigating the situation which led to these results," AK said in a statement.
"Appropriate follow-up action will be taken in Kenya. Athletics Kenya will provide full support and cooperation to the IAAF during the results management process."
