In this Aug. 22, 2010, file photo, Sherone Simpson, of Jamaica, runs to win the women's 100-meter event during the ISTAF Athletics Meeting in Berlin. Former 100-meter world-record holder Asafa Powell and teammate Simpson have each tested positive for banned stimulants, according to their agent. Paul Doyle told The Associated Press on Sunday, July 14, 2013, that they tested positive for the stimulant oxilofrine at the Jamaican championships and were just recently notified. (AP Photo/Markus Schreiber, File)

In this Aug. 22, 2010, file photo, Sherone Simpson, of Jamaica, runs to win the women’s 100-meter event during the ISTAF Athletics Meeting in Berlin. Former 100-meter world-record holder Asafa Powell and teammate Simpson have each tested positive for banned stimulants, according to their agent. Paul Doyle told The Associated Press on Sunday, July 14, 2013, that they tested positive for the stimulant oxilofrine at the Jamaican championships and were just recently notified. (AP Photo/Markus Schreiber, File)

(Reuters) – Jamaican Olympic relay silver medalist Sherone Simpson said on Sunday she had tested positive for a stimulant at last month’s national championships.

Simpson, 28, was a member of the Jamaican team that finished second in the 4×100 relay at last year’s London Olympics.

She finished equal second in the 100 meters at the 2008 Beijing Games and won a gold medal in the 4×100 relay four years earlier in Athens.

“This is a very difficult time for me,” Simpson said in a statement to Reuters.

“I was notified on July 14, 2013 that my urine sample taken at the National Senior Championship, June 21, 2013 after the 100m finals returned a positive analytical finding for a stimulant, oxilofrine (methylsynephrine).

“As an athlete, I know I am responsible for whatever that goes into my body. I would not intentionally take an illegal substance of any form into my system.”

(Reporting by Gene Cherry in Raleigh, North Carolina; Editing by John Mehaffey)