Jamaica's Traves Smikle competes in the men's discus qualification during the London 2012 Olympic Games at the Olympic Stadium August 6, 2012. REUTERS/Pawel Kopczynski

KINGSTON (Reuters) - 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 (JADCO) 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.

“Personally, I am very saddened and surprised by these findings, as I have never attempted to cheat and have always considered myself an ambassador for the sport and a strong supporter of drug testing.”

Smikle, who competed for Jamaica at last year’s London Olympics but did not make the discus final, also said he regretted the “hurt and embarrassment” his failed test caused a country still digesting news of positive tests from two high-profile sprinters and another discus thrower.

He joined former world 100 meters record-holder Asafa Powell, Olympic 4x100m relay silver medalist Sherone Simpson and fellow discus thrower Allison Randall, as athletes to confirm doping violations from the Jamaican trials.

Sources close to Jamaican athletics said a fifth athlete, a junior who has not been identified, had also tested positive for banned performance-enhancing drugs at the championships.

Smikle, 21, has requested analysis of his ‘B’ sample and was willing to work with JADCO in any investigation to get this matter dealt with in the best way possible.