Jamaican sprinter Steve Mullings, the third fastest man over 100m this season, has tested positive for a banned substance, his agent John Regis confirmed on Friday. The 28-year-old, who has a best of 9.80sec this season and would have been a medal contender at the world championships later this month, could now face a life ban after already having served a two-year doping ban for steroids from 2004-2006. Regis said that Mullings was notified of the result at the start of the week by the Jamaican anti-doping body (JADCO). JADCO had confirmed on Thursday that an athlete had failed a drugs test after being tested on June 24 at the national championships, but they had not identified the competitor. Regis did not give details of the substance involved and that Mullings's 'B' sample will be tested, probably on Tuesday in Montreal. Mullings had already qualified for the world championships after finishing third in the 100m at the national trials behind world record holder Asafa Powell and Yohan Blake as well as by winning the 200m, his favoured event. He was fifth in the 200m at the 2009 world championships in Berlin and was part of the gold medal winning 4x100m relay team.