Kenya's Olympic committee has sent home an athletics coach from the Rio Games after he posed as an athlete and gave a urine sample to drug testers, deepening concerns about the country's efforts to tackle doping, which has tarnished its reputation.

John Anzrah was sent home on Thursday after a drug test at an Olympic venue, according to Kip Keino, chairman of the National Olympic Committee (NOC) of Kenya.

"He presented himself as an athlete, gave the urine sample and even signed the documents. We cannot tolerate such behaviour," said Keino.

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"We don't even know how he came here because we did not facilitate his travel here."

The International Olympic Committee (IOC) has launched disciplinary proceedings against the coach.

"We take note of the decision of the Kenyan Olympic Committee to send home its athletics coach following a violation of anti-doping rules and we thank the NOC for its swift action," said an IOC spokesperson.

"The IOC has immediately created a disciplinary commission to look into the matter with regard to the coach and the athlete concerned."

The East African nation boasts some of the world's best middle and long-distance runners, but more than 40 of its competitors have failed drug tests since 2012 and its athletics federation has been mired in corruption scandals linked to doping.

The concerns over Kenya's doping problem were so large that at one point the country's participation at the Olympics was under threat.

Last week, Kenya sent their track and field manager Michael Rotich home from Rio 2016 following allegations that he requested money to let undercover journalists, posing as athlete representatives, know when drugs testers would come calling.

Rotich denied the accusations but was arrested on his return to Nairobi, where a judge ordered the police to hold him for four weeks during the doping probe.

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Source: Agencies