The 28-year-old Kenyan has also been charged with tampering for allegedly "obstructing or delaying the AIU's investigation through the provision of false information or documentation."

Kipyokei won the women's race in Boston - which is one of the World Marathon Majors - on October 11 last year but failed a test immediately afterwards.

She is one of two Kenyan marathon runners to be provisionally suspended today, alongside Betty Wilson Lempus who faces a tampering charge.

The AIU said that Kipyokei would be disqualified as Boston Marathon champion if the allegations against her are proven.

Another Kenyan, two-time world marathon champion Edna Kiplagat, finished second so is in line to move up.

The winning time was 2hrs 24min 45sec with Kipyokei, whose surname has also been spelt Kipyogei, beating her team-mate by 24 seconds.

"After extensive investigations, the Athletics Integrity Unit has provisionally suspended two Kenyan marathoners - Diana Kipyokei and Betty Wilson Lempus - and charged them with various breaches of the World Athletics Anti-Doping Rules," an AIU statement said.

"These alleged anti-doping rule violations stem from probes into the information provided by the athletes to explain adverse analytical findings (AAF) for metabolites of triamcinolone acetonide in samples they provided during in-competition tests last year. 

"Both athletes were questioned about their AAF, and their respective explanations (including supporting documentation) were subjected to detailed investigation by the AIU, with vital assistance from the Anti-Doping Agency of Kenya.  

"Ultimately, the AIU's findings led to the charges being announced today."

Lempus won the Harmonie Mutuelle Semi de Paris race on September 5 last year before testing positive.

She was originally cleared of wrongdoing by the French Anti-Doping Agency following her explanation for the AAF, but the AIU then conducted its own investigation.

Following Lempus' explanation, she has, like Kipyokei, been accused of obstructing or delaying the AIU probe by providing false details.

Triamcinolone is usually used to treat skin conditions and rheumatic disorders and is included on the World Anti-Doping Agency banned list.

It has become a problem substance in Kenyan athletics as 10 athletes tested positive between 2021 and this year.

The AIU said that in the same period globally, only two athletes from other countries had failed a test for triamcinolone.

Only three Kenyans tested positive between 2017 and 2020, suggesting a growing trend.

Mark Kangogo, a Kenyan who won the Sierre-Zinal 2022 mountain race in Switzerland, was yesterday banned for three years after triamcinolone was detected in his sample.

Four other cases involving Kenyans and the substance are currently ongoing at the AIU.