Kenyan 800m runner and 2017 World bronze medalist Kipyegon Bett has tested positive for the banned substance Erythropoietin (EPO), Athletics Kenya (AK) said on Friday. Athletics Kenya executive committee member Barnabas Korir said that AK was alerted to the positive sample by the Athletics Integrity Unit on Thursday.

Bett’s B sample has yet to be tested, but should it return positive he will likely be given a four-year ban from the sport.

The 20-year-old Bett was handed a provisional suspension on August 15 after he failed to provide a sample for testing. Korir told Reuters that Athletics Kenya submitted a defense for Bett on that matter yesterday, but then they were subsequently notified by AIU that his sample tested positive for EPO.

Bett last raced on June 10 in Stockholm. In 2017, he was the only Kenyan 800m runner to make the IAAF World Championship final in London, finishing third in 1:45.21. He narrowly beat out Great Britain’s Kyle Langford for a medal by .04 seconds.

Langford tweeted his displeasure with Bett on Friday:

I mean would have been nice to get a medal at a home champs in front of the British crowd. Thanks bett?

— Kyle langford (@KyleLangford_96) August 24, 2018

Bett is the latest in a series of prominent athletes from Kenya to test positive for a banned substance. Earlier this year, 2008 men’s 1,500m Olympic gold medalist Asbel Kiprop and Kenyan-born Ruth Jebet of Bahrain, the 2016 women’s Olympic 3,000m steeplechase gold medalist, were also found to have EPO in their samples, the AIU confirmed. 

Kiprop has repeatedly denied breaking anti-doping rules, and has stated that he believes his sample was tampered with. The three-time world champion claimed that he was extorted for money by the officials, and that he was offered an ambassadorship role with IAAF should he accept a doping ban. The Athletics Integrity Unit has dismissed Kiprop’s claim about him being offered such a role.