BEIJING - Teenage swimming world champion Li Zhesi has tested positive for banned substance, China Anti-Doping Agency (CHINADA) announced here on Saturday.

Li was found positive for blood-boosting drug erythropoeitin, or EPO in an out-of-competition test carried out on March 31, said CHINADA.

"The drug was found both in the A and B samples," it said in the announcement, adding that the punishment has yet to be decided.

Li, 16, is a promising star in Chinese swimming. She was a winning team member in the 4x100m medley relay event at the 2009 Rome world championships.