The China Swimming Association has admitted that one of its top hopes for a medal at the Beijing Olympics has tested positive for a banned substance, a development that will increase international suspicions on the country's commitment to the anti-doping cause. Zhou Jie tested positive for the anabolic steroid clenbuterol in an unannounced, out-of-competition test taken in September by the World Anti-Doping Agency (Wada). The 15-year-old was suspended by the International Swimming Federation (Fina) on November 24, and yesterday the China Swimming Association said it would abide by the suspension. 'We will respect Fina's decision and we will continue our fight against doping,' Shang Xiutang, vice-president of the China Swimming Association, said. He added that he believed Zhou had inadvertently consumed the banned substances after eating some grilled lamb kebabs bought from a street vendor. 'However, no matter if Zhou took the substance by mistake or not, we accept [Fina's] decision,' he said. Zhou took bronze in the 800m freestyle at the National Games in October, clocking the 19th fastest time in the world this year. She later came fourth in the 1,500m freestyle at the East Asian Games in Macau. Clenbuterol helps athletes build muscle mass and increase endurance levels. Zhou is the fifth Chinese swimmer to be suspended for a doping offence since 2001. This latest positive test will increase concerns in the international swimming community that the use of performance-enhancing drugs is still widespread in China, despite repeated pledges by Beijing that a systematic doping policy is a thing of the past. Over the past few months, some top-level international coaches have made serious allegations against China's swimmers. What has stoked most concern was the surprise appearance in Shanghai this year of Helga Pfeiffer, a notorious 'Stasi drug criminal' who was the head coach of the East German swimming team and responsible for pumping her young charges full of steroids in the days before the fall of the Berlin Wall. According to Chinese swimming officials, she was helping them install a new flume - the aquatic equivalent of a treadmill in which athletes swim on the spot against fast-flowing water. But John Leonard, head of the American Swimming Coaches Association, was suspicious and wrote a paper entitled Fears and Facts: presence of East German doping criminal raises fears about China's intentions to draw international attention to Pfeiffer's apparent comeback. In his paper, he called on Wada to ban her from the sport for life and urged China to 'recognise the total and absolute wrongness of allowing this criminal to work in their nation, and toss her out on her ear'. Leonard also believes that 50 elite Chinese swimmers have 'gone missing' since 2001, and are training in secret - far away from international competitions and anti-doping officials - and the best of them will appear again shortly before the 2008 games. He said a Chinese coach had told him these covert training programmes used 'a variety of sophisticated doping methods and perhaps the brave new world of genetic enhancement'. A China Swimming Association official yesterday denied any knowledge of a secret training camp. The official, who refused to give his name, said he did not know precisely what Pfeiffer's role was, but said China would 'continue its fight against doping'. Following the World Championships in Montreal in July, United States coach Dave Salo also raised suspicions that China was keeping its best swimmers out of competitions so they could avoid international drug testing in the run-up to the Olympics. China won only five medals in Montreal, compared to 32 for the US. 'When they're not participating to the extent you'd expect them to be here, you wonder: What are they doing? Who are they hiding?' Dick Pound, chairman of Wada, dismissed Salo's claims, citing a lack of evidence. 'People didn't like it when China was winning and they don't seem to like it when the Chinese are not winning. What do the Chinese have to do? If there's a problem, identify it. If there's not a problem, keep quiet,' he said. The international reputation of Chinese swimmers was severely tarnished in the 1990s when they came from seemingly nowhere to become a major force in the pool. But the glory quickly turned to shame after nearly 40 of their swimmers subsequently failed drug tests.