US transgender powerlifter Mary Gregory was stripped of records she set last month at a national competition after a doping test revealed that the athlete “was actually a male in the process of becoming a transgender female.”

Gregory broke four women's world records during the competition in the squat, bench press and deadlift disciplines as well as total record in her weight class.

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Following the event, Gregory thanked the US Powerlifting Federation for allowing her to take part in the competition as a female lifter.

However, the federation didn’t share enthusiasm over Gregory’s record-breaking performance after the obligatory doping control proved that the athlete should have performed in men’s category.

“The lifter exceeded the current female world records in this lifter’s age and weight category. This automatically calls for drug testing protocol which takes place at the end of every event. The drug testing coordinator for this event performed the drug test at which time it was revealed that this female lifter was actually a male in the process of becoming a transgender female,” the federation said in a statement.

“Our rules, and the basis of separating genders for competition, are based on physiological classification rather than identification. On the basis of all information presented to the Board of Directors for this particular case, the conclusion made, is that the correct physiological classification is male.”

The US powerlifting governing body annulled Gregory’s records admitting that the athlete should not have competed against women.

“Since the lifter’s gender classification for the purpose of our rules is not consistent with female, no female records will be broken by these lifts,” the statement reads.