Jamaican sprinter Asafa Powell has described his 18-month ban for doping as 'unfair and patently unjust'.

The former 100m world record holder was issued with the sanction by the Jamaica Anti-Doping Commission on Thursday.

The ban is in relation to last June when he tested positive for banned stimulant oxilofrone at Jamaica's national trials.

Powell has claimed that he unknowingly took the substance that he has stated was contained in legal supplement Epiphany D1.

In a statement, Powell said: "This ruling is not only unfair, it is patently unjust. Panels such as these, I understood, were assembled to allow athletes who consciously or unconsciously come into conflict with the rules of sport a chance at equitable redemption. Unfortunately, this was not the case."

The ban was backdated to June 2013, which means that Powell can compete once again from December 20.