Cycling Canada has issued a statement over revelations that Clara Hughes tested positive for a banned substance more than 20 years ago.

The national cycling body says it was contacted by Hughes in late August, and told that her upcoming biography would contain revelation of a previously non-disclosed anti-doping rule violation.

Hughes "provided Cycling Canada with a copy of the manuscript excerpt which reveals that she had tested positive for the banned substance ephedrine in 1994 and further indicates that she was notified of this by the then National Team Director who had received the notice of a three month sanction from the UCI (the International Cycling Union)," Cycling Canada said in a statement released Sunday.

In her biography, Hughes writes that she and three others intentionally kept quiet about the sanction, Cycling Canada said.

Cycling Canada said that, while the rules and regulations regarding the disclosure of anti-doping rule violations are vastly different today compared to 1994, it cannot condone the way the matter was handled.

"Regardless of the practices of the day, Cycling Canada believes in full, fair and open disclosure of all doping related offences," the statement said.

"Cycling Canada is proud of its current role as a leader in the anti-doping movement and remains committed to learning from the mistakes of the past so we don't make them again."

Hughes' memoir, "Open Heart, Open Mind," is due out on Tuesday.

In an interview with CBC News, she said she got a call informing her that she had tested positive for ephedrine a few months after the cycling world championships in Sicily.

She said she has no idea how the drug got into her system, and wonders if the lab made a mistake with her urine samples or if she had been sabotaged.

She said she was given a three-month suspension, and was advised to keep the violation a secret.

Following the interview, Hughes tweeted that it was the "most difficult" she's ever done.

Throughout her athletic career, the 42-year-old has become a household name, as she excelled in both cycling and speed skating.

The Winnipeg native is one of the few athletes who have competed in both the Summer and Winter Olympics, winning multiple Olympic medals in both sports.

In recent years, she's focused her attention on breaking down the stigma surrounding mental health issues, becoming a high-profile participant in Bell's Let's Talk campaign.

Last year, Hughes embarked on a cross-country bike ride, dubbed "Clara's Big Ride," in a bid to connect Canadians, while raising awareness on mental health illness.