Ruth Chepngetich, the Kenyan who shattered the women's marathon world record lyear, has been provisionally suspended on suspicion of doping, the Athletics Integrity Unit said on Thursday.
Chepngetich, who improved the record to 2hr 09min 56sec in Chicago in October, has been suspended after testing positive for the banned diuretic hydrochlorothiazide on 14 March this year.
AIU head Brett Clothier said 30-year-old Chepngetich's case was being investigated and would be heard by a disciplinary tribunal.
"When there is a positive test for diuretics and masking agents, a provisional suspension is not mandatory under the World Anti-Doping Code," he explained.
"Chepngetich was not provisionally suspended by the AIU at the time of notification. However, on 19 April she opted for a voluntary provisional suspension while the AIU's investigation was ongoing.
"In the intervening months, the AIU continued its investigation and today issued a Notice of Charge and imposed its own provisional suspension."
In April, Chepngetich withdrew from the London Marathon, saying she was "not in the right place mentally or physically to race my best".
Hydrochlorothiazide is used to treat fluid retention and hypertension.