NAIROBI (Reuters) - Kenyan athletics coach John Anzrah was sent home from the Rio Olympics after he posed as an athlete and gave a urine sample in a doping test, Kenya's Olympics chief told Reuters on Thursday.

Anzrah is the second Kenyan official to be sent home from the Games over drugs allegations, deepening doping concerns which have dogged Kenya for much of the past year after several runners tested positive for performance enhancing drugs.

Kip Keino, a Kenyan running great and chairman of the National Olympic Committee of Kenya (NOCK), said sprint coach Anzrah was sent home after being caught out following a drugs test at an Olympic venue.

"He presented himself as an athlete, gave the urine sample and even signed the documents. We cannot tolerate such behaviour," Keino said in a telephone interview from Rio after a Kenyan media outlet reported Anzrah had been sent home.

"We don't even know how he came here because we (NOCK) did not facilitate his travel here," added Keino.

It was not clear which athlete Anzrah was pretending to be. But one senior source at Kenya's running federation, Athletics Kenya (AK), said he had spoken to the concerned athlete who claims Anzrah used his accreditation purely to obtain free meals from athletes' village.

"When the anti doping officials met him, they assumed he was the athlete and that he was lined up for testing," said the Athletics Kenya source.

"The coach, for fear of being exposed or discovered, did not explain to the anti-doping guy that he is actually not the athlete. Hence he played along and went for the test," added the AK source.

Anzrah was not immediately available for comment.

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