KARACHI (AFP) - Pakistan's troubled fast bowler Mohammad Asif, who has faced multiple doping charges, told prosecutors in Dubai he thought the opium found in his possession was a herbal remedy, a report showed Sunday. Asif, 26, was detained in the Gulf emirate for nearly three weeks in June last year for possession of a banned substance before public prosecutors determined the amount of the drugs was insignificant and deported him. A prosecutors' report, a copy of which was obtained by AFP, reveals Asif - who faces a two-year ban from an Indian doping tribunal on a separate offence - confessed to using the substance, but said he did not know it was opium. "I think it's a herbal dark substance found with me which I use for energy... to reduce blood pressure and gain energy. I have obtained it from one of the public curers in Pakistan," the report quoted Asif as saying. "I started using it once every year, by one small piece each time when necessary," he told investigators. "I did not intend to bring it to the country and I don't know whether it is a narcotic drug or otherwise, and I don't know whether it is prohibited in the UAE or not." A urine sample taken in Dubai tested negative for banned substances. But a month after his arrest in Dubai, the Indian Premier League (IPL) said Asif had tested positive for the banned steroid nandrolone. A three-man IPL doping tribunal is set to hear the case in London on January 24. The Pakistan Cricket Board has suspended Asif from all forms of the game pending the result of the IPL inquiry. Asif also faces a possible ban or fine from the PCB over the Dubai incident. Cricket authorities said Sunday they were not yet aware of the report from Dubai prosecutors and would not act until they had reviewed it. The fast bowler previously tested positive for nandrolone just before the 2006 Champions Trophy in India. He was banned for one year by a PCB tribunal, but that punishment was overturned a month later on appeal. Asif has played 11 Tests and 31 one-day matches for Pakistan since making his debut in Australia in early 2005.