Olympic discus thrower Traves Smikle on Thursday became the fourth Jamaican athlete in four days to reveal a positive doping test but said he did not knowingly ingest a banned substance.

Smikle said the Jamaica Anti-Doping Commission notified him that his urine sample from the Jamaica National Trials in June returned an adverse analytical finding. He did not identify the substance for which he tested positive.

"As an athlete, I must take responsibility for whatever is found in my body; however I wish to state that I did not knowingly or willfully ingest any banned substance," Smikle said in a statement.