NEW YORK • Top-ranked female mixed martial arts featherweight Cris "Cyborg" Justino has been informed by the United States Anti-Doping Agency (Usada) of a possible doping violation, the Ultimate Fighting Championship (UFC) said on Thursday.

The UFC said in a statement it was formally notified that Usada told Justino of a potential anti-doping policy violation stemming from an out-of-competition sample collection on Dec 5.

Usada, the independent administrator of the UFC's anti-doping policy, would handle "the appropriate adjudication of this case," the UFC said, adding that a full review process was assured under the policy before any sanctions may be imposed.

While Usada did not reveal any details of the doping test, Justino wrote on her Facebook page that she had tested positive for the diuretic spironolactone.

"It has been brought to my attention that my recent sample contained a banned substance known as spironolactone," she said. "The substance is part of a therapeutic treatment being administered to me by my doctor that started on the 26th of September and is supposed to last for a period of no less than 90 days, requiring blood exams at the completion.

"We are fully cooperating with Usada at this time and have already started the process of applying for a retroactive therapeutic use exemption."

Justino last fought on Sept 24, stopping Lina Lansberg in the second round as part of a UFC Fight Night event in her native Brazil.

The 31-year-old (17-1 win-loss record) previously tested positive for an anabolic steroid in December 2011, which she blamed on a diet supplement she received from a former coach.

REUTERS