Kenya's Diana Kipyokei, winner of the 2021 Boson Marathon, was suspended on Friday after testing positive for doping at the race and allegedly obstructing an investigation.

The Athletics Integrity Unit (AIU) said Kipyokei's sample after winning in October last year had traces of triamcinolone acetonide. It is a glucocorticoid prohibited at races when an athlete does not have permission to use it as a medication.

The case has deepened suspicions the substance is a doping product of choice for athletes from Kenya.

The AIU said 10 Kenyans have tested positive for triamcinolone since the start of 2021, with only two cases in athletics from the rest of the world in the same period.

In a second triamcinolone case revealed on Friday, Kenyan marathon runner Betty Wilson Lempus was also suspended while under investigation for doping and tampering.

Kipyokei is also under investigation for "obstructing or delaying the AIU's investigation through the provision of false information or documentation."

The AIU did not elaborate about the suspected tampering, which could be related to a Therapeutic Use Exemption (TUE) document athletes need to have before using a medication that is otherwise prohibited.

The 28-year-old Kipyokei faces being banned for at least four years and stripped of her Boston win and $150,000 prize money.

"Kipyokei's result in the 2021 Boston Marathon will be disqualified, pending the completion of relevant athlete appeals processes," the Boston Athletic Association (BAA), organizer of the race, said in a statement. "The BAA will adjust race rankings and will provide prize award adjustments to top finishers of the 2021 event, pending the sanctioning."

Kipyokei won the Boston women's race in 2 hours, 24 minutes, 45 seconds, which was 24 seconds ahead of her Kenyan compatriot Edna Kiplagat.

Kiplagat, a two-time world champion in the marathon who turns 43 next month, is set to get her second Boston title. She also won in 2017.

A high-profile case of an athlete having a valid TUE for triamcinolone involved British cyclist Bradley Wiggins who was permitted to take it in 2012 before winning the Tour de France.