Ruth Jebet, the reigning Olympic 3,000m steeplechase champion and world record holder, has become the highest-profile Kenya-born athlete to become embroiled in a drug-testing scandal.

Although the news has not yet been confirmed, a number of prominent sources have suggested Jebet has tested positive for a performance-enhancing drug, believed to be the blood booster EPO.

The Athletics Integrity Unit, which processes all doping tests in track and field, said it was unable to confirm the result of any tests under the World Anti-Doping code. Meanwhile, Jebet’s agent, Marc Corstjens, said he had not heard any news of a positive tests. “Honestly I am surprised and shocked. I am absolutely not aware of anything. I tried to reach Ruth but her phone is not answering. I have absolutely no official information.”

The 21-year-old is seen as one of athletic’s brightest stars having won a stunning gold medal at the 2016 Rio Olympics before shattering the world record while still a teenager. She is also a controversial figure in Kenya, having switched allegiances to run for Bahrain after being approached as a 16-year-old and promised a full scholarship to take an animal health degree in the country.

Yet with Jebet spending most of her time training in Kenya, this may raise more questions about how many of the country’s athletes are clean – and whether enough is being done by the authorities to find out.

Between 2011 and 2016, more than 40 athletes from Kenya failed doping tests, including Rita Jeptoo, the three‑times Boston marathon champion, who was given a four-year ban after testing positive for EPO in 2014.

Last year Jeptoo’s former training partner, the Olympic and London marathon winner Jemima Sumgong, was also banned for four years after her claim she was taking EPO for an ectopic pregnancy was rejected.

Yet if Jebet’s failed test is confirmed it will be a bigger shock still. When she took gold in the women’s 3,000m steeplechase at Rio in 8:59:75 – at that point the second-fastest time in history – she was hailed as “Golden Ruth”, although she was greeted with boos in her homeland because she beat Kenya’s Hyvin Jepkemoi into second.

It emerged the Bahrain government had paid Jebet a $500,000 bonus for her Olympic success. By contrast David Rudisha, who won the 800m in Rio in a Kenyan vest, received $10,000 from his government.

Two years ago Kenya was deemed “non-compliant” by Wada but it was reinstated before the Rio Olympics. However, many athletes have suggested not enough is done to test athletes training in the country. The Canadian runner Reid Coolsaet said in 2016: “Kenyan-style anti-doping test. Notify us the night before. One-hour drive to test site at 5am. Many Olympic medallists in house. It was an IAAF accredited test. Procedures are far from what I’m used to in Canada.”

In 2013 another high-profile Kenyan, Matthew Kisorio, told the German broadcaster ARD he took illegal drugs “because everyone told me, I wasn’t the only one – and none of the others got caught for doping”.

He added: “I know a lot of medical substances are used, which are injected straight to the blood for the body to have more oxygen. And when you run, you run so smooth. You have more stamina.”