Ethiopian athletics has been rocked by the news that marathon runner Ambesse Tolossa has been convicted of a doping offence and has been banned from all competitions for the coming two years.

The 29-year old, who was a member of Ethiopian national teams in the last Olympics in Athens and the last two editions of the IAAF World Championships, failed an in-competition doping test for the banned substance morphine after winning the 2007 Honolulu Marathon last December. He has now been stripped off his title and will not receive the prize money winnings, USD 40,000, which was pending clearance of a drugs test.

The Ethiopian Athletics Federation (EAF) has now banned the athlete for two years through Feb. 4, 2010.

In an exclusive interview with IAAF's correspondent Elshaday Negash, Ambesse has denied knowingly taking any banned substance. "I have not knowingly taken any banned substance," he said. "I do not even know what morphine is before I was informed by the Ethiopian Athletics Federation that I had taken the substance."

He says he is yet unsure about his next course of action: whether to accept the ban or appeal the decision with the International Association of Athletics Federations (IAAF) or the Court of Arbitration for Sport (CAS).

"I have been told that I have no choice but to accept the ban," he said. "I still do not know how the substance got into my body and if given the opportunity, I want to prove my innocence."

In Olympics sports, there is a strict liability policy, meaning that an athlete is responsible for any banned substance which enters his or her body, regardless of intent. However, penalties are usually reduced for inadvertent violations if the athlete can demonstrate such was the case.

Unlike many of the world's high profile doping cases, Ambesse did not test positive for a performance-enhancing drug like EPO or steroids, but morphine, which is a strong pain reliever found in both his "A" and "B" test samples. Opiates are included in the World Anti-Doping Agency's list of prohibited substances.

Ambesse claims that he had taken pain relievers two times before his test returned positive. He has presented evidence that he took medication to relieve pain caused by food poisoning, but no residues of morphine have been identified in that medicine. He has yet to present evidence that he was also injected with an analgesic during a dental operation last year.

"Since this is a first offence, he will be ineligible for two years," said Ayalew Tilahun, Ethiopian team doctor. "The whole process has taken us around six months after Ambesse denied taking any banned substances. But the evidence is conclusive and overwhelming and he has now been informed of the ban."

Ambesse's is the first high profile doping offence by an Ethiopian athlete after Alene Emere Reta was also sanctioned after an out-of-competition drugs test in 2003 while he was competing in Japan. He now competes in the United States.