(CNN) -- Asafa Powell, the last man to hold the 100m world record prior to his compatriot Usain Bolt, admitted to a Jamaican disciplinary hearing on Tuesday that he had a hazy knowledge of the World Anti-Doping Agency's list of banned products
The 31-year-old was testifying to the Jamaican Anti-Doping Commission (JADCO) after testing positive for the prohibited stimulant oxilofrone during last June's national championships.
The oxilofrone is said to have come from a supplement called Epiphany D1, which Powell said he had been taking on the recommendation of his physical therapist Christopher Xuereb.
"I don't know the list but I knew of the list," Powell said at the hearing in the Jamaican capital Kingston.
"I know there is a list we are supposed to check."
When asked whether he was acquainted with the rules of doping control, the once fastest man on the planet wistfully replied: "I am now."
Powell, whose 100m world record mark of 9.74 seconds was beaten by Bolt in 2008, also said that he failed to list all the supplements he was taking during the Jamaican trials because he could not recall the relevant names.
"All the supplements were new to me, so I could not remember all of them," he explained, adding that he started taking them roughly a month before the Jamaican championships began on June 20.
Among the absentees from the list was Epiphany D1.
"I could not remember after all the excitement at the trials," the Jamaican said.
Powell also told the hearing that he doubled the dosage of his supplements on the morning of his positive drugs test, saying he had been told by Xuereb to take two capsules of Epiphany D1 each morning for seven days before doubling the dosage the following week.
"I didn't remember to do that," said Powell, whose hearing is expected to last at least two days.
"Chris (Xuereb) came to my room the morning of the trials and said I must remember to take four."
Powell says he was advised to take the supplements after Xuereb, who the sprinter described as a good friend, told him he should be using them ahead of his early morning training.
Prior to that, the Jamaican had regularly trained without consuming anything - not even breakfast, he explained.
Powell's hearing before a three-member panel comes after his training partner Sherone Simpson, a three-time Olympic medalist, was also forced to explain her positive test for the same stimulant.
Like Powell, she denies knowingly taking the banned stimulant and her case earlier this month was adjourned until February 4.
The athletes have been provisionally suspended since their failed tests, with both missing out on last year's World Championships in Moscow.
A total of five Jamaican athletes failed drugs tests at the national championships in June, prompting the entire JADCO board to resign five months later -- with criticism over a lack of testing by the body's former executive director Renee Anne Shirley ringing in their ears.
The hearing will resume on Wednesday, with agent Paul Doyle - who represents both Powell and Simpson - set to testify.