A top female marathoner tested positive for drugs, consequently postponing the World Marathon Majors awards ceremony, according to a statement from the organization on Friday. The athlete’s agent, Federico Rosa, could not be reached for comment but reportedly told the Associated Press that her client, Rita Jeptoo of Kenya, had failed the doping test. Jeptoo was to be awarded the World Marathon Majors women’s champion along with its $500,000 prize on Sunday. Jeptoo’s victories at the Boston and Chicago marathons this year sealed her series title, regardless of the outcome in Sunday’s New York City Marathon.

“World Marathon Majors is disappointed to learn that Rita Jeptoo has apparently had an A test that proved positive for a banned substance under IAAF rules,” the statement read. “At present there has been no decision in this case by the [International Association of Athletics Federations], including in relation to sanctions, and as a result WMM is unable to comment further until that determination has been made although in the circumstances it has been decided to postpone the WMM Awards Ceremony that was due to take place on the 2nd November 2014.”

The organization also noted that any athlete found guilty of doping would not be invited back to its races, a series consisting of six of the largest and most prestigious marathons in the world: Tokyo, Boston, London, Berlin, Chicago and New York City.

“WMM has always held a stern line on drugs cheats and has been proactively the sport’s governing bodies to ensure the integrity of the athletes competing in their races. Cheats need to understand that they are not welcome in our sport and they will be caught,” said Nick Bitel, general counsel of the World Marathon Majors.

Jeptoo, 33, failed a doping test in September, just a few weeks before defending her title in the 2014 Chicago Marathon in October, according to RunBlogRun’s Larry Eder, who first reported the news. In an out-of-competition testing procedure in Kenya, Jeptoo tested positive in her A sample for a banned substance. Her B sample collected at the same time will now be tested.

Chicago Marathon race director Carey Pinkowski released a statement to ESPN on Friday, saying the organization wait until the IAAF’s final ruling on the matter before addressing Jeptoo’s standing with the Chicago Marathon.

Boston Athletic Association executive director Thomas Grilk told the Boston Globe that Jeptoo passed her doping tests at this year’s Boston Marathon, which she won for the second straight year and third time overall. “Top finishers at Boston are tested through the procedures established by and are conducted under the auspices of the IAAF. The athlete was tested at Boston, and the IAAF informed us that all tests from this year’s Boston marathon were negative,” Grilk told the Globe Friday. The Boston Athletic Association released a statement on their website Friday, saying the organization also awaits an official statement from the IAAF before addressing the matter. Jeptoo set a women’s record at the 2014 Boston Marathon in April, finishing with a time of 2:15:57.