The athlete and Athletics Kenya had both announced the positive test, with the AIU now confirming the breach of anti-doping rules.

Bett, who won 800m bronze at last year's World Championships in London and claimed the world junior title in the same event in 2016, is now facing a lengthy ban from the sport.

"AIU confirms the issue of a Notice of Allegation against Kipyegon Bett for a violation of Article 2.1 of the Anti-Doping Rules,” the AIU stated.

"The Kenyan runner is already provisionally suspended from all competition for an earlier violation of Article 2.3."

The 20-year-old is already serving a provisional suspension for evading a drugs test.

The AIU announced last week that the 800m specialist was provisionally suspended for "refusing or failing to submit to sample collection".

Bett claimed bronze at last year's World Championships in London in the 800m in a time of 1min 45.21sec in London to end behind silver medallist Adam Kszczot of Poland and French winner Pierre-Ambroise Bosse.

British runner Kyle Langford, who reacted with sarcasm on social media at the announcement of the failed test, ended 0.04 seconds behind the Kenyan.

Bett is one of 18 Kenyans currently provisionally suspended for a breach of anti-doping rules.

Three-time Boston Marathon champion Rita Jeptoo and Jemimah Sumgong, the Olympic marathon gold medallist at Rio 2016, on the list of high-profile Kenyan athletes who are currently serving suspensions for doping offences.

Reigning Olympic steeplechase champion Ruth Jebet, who now represents Bahrain but continues to train and live in Kenya where she was born, has also been suspended since February following an EPO failure.

A further four are provisionally suspended by the AIU, including Athens Marathon champion Samuel Kalalei, distance runner Lucy Wangui Kabuu and sprinter Boniface Mweresa.

A case is also pending against three-time world champion and Beijing 2008 Olympic gold medallist Asbel Kiprop after he tested positive for EPO in an out-of-competition test in November 2017.

Bett's case is a further blow to Kenyan athletics.

The International Association of Athletics Federations (IAAF) included the distance-running superpower on a list of nations most at risk of doping in July.

It came as part of new regulations by the IAAF Council which put more responsibility on National Federations to deal with the problem.

Kenya and Ethiopia were among four countries included in Category A - member federations the IAAF believe are most likely to have doping problems - along with Belarus, hosts of next year's European Games, and Ukraine.

Athletics Kenya last week announced the establishment of an Oversight Committee as they seek to tackle the spate of doping cases involving their athletes.