Moroccan 1,500 metres runner Mariem Alaoui Selsouli will miss the Olympics after testing positive for a banned drug.
Selsouli has already served a two year suspension for doping and now faces a lifetime ban.
She was the gold medal favourite, after winning the Paris Diamond League meeting earlier this month.
However, questions were asked after the Moroccan took four seconds off her personal best, with the fastest time in the world since 2006.
She later tested positive in Paris for banned diuretic.
Selsouli was banned for two years in August 2009 for using the banned performance enhancing blood booster Erythropoietin
(EPO).
