Only 42 days before the opening of the Olympic Games in Beijing, Ouyang Kunpeng, China's top backstroke specialist, has dealt a blow to the notion that the host nation has held its swimming team behind a ring of steel and out of the reach of doping. The swimmer has been banned for life - as has Feng Shangbao, his coach - after testing positive for clenbuterol, the anabolic steroid, on May 1.

Ouyang, No 3 in the world in the 100 metres backstroke and No 7 in the 200 metres in 2005, is the 46th Chinese swimmer since 1993 to test positive for banned substances. Most of those involved the use of steroids in the 1990s, when China's doping crisis rattled Fina, the sport's governing body, into taking much tougher measures in the fight against cheating.

The 25-year-old Ouyang, who comes from the southern province of Jiangxia and had been selected to represent China at the Games, had fallen away from his best form of late. A source told The Times: “Now that most of the [China] swim team is known, some will feel safe to return to methods that they had tried and tested in the early years of their career once back in their provinces.”

Among those who will be glad that Ouyang is out of the Olympics is Liam Tancock, of Great Britain, a double bronze medal-winner - in the 50 metres and 100 metres backstroke - at the World Championships in Australia last year.

China's doping crisis came to a head when enough human growth hormone to supply the entire national team was found in the bags of Yuan Yuan, a swimmer, by customs officers at Sydney airport in January 1998 as she made her way to the World Championships in Perth. In the investigation that followed, the Chinese Swimming Association admitted that it had no control over what was happening in the provinces.

In 2002 a plan was hatched to keep those likely to qualify for the Olympic team in a ring-fenced environment at the national training centre in Beijing, to keep swimmers and coaches away from suppliers and corrupt local officials.

Under Fina rules, first-time offenders for anabolic steroids used to receive four-year suspensions until World Anti-Doping Agency rules watered down the penalty to two years. China imposed a life ban to send out a stern warning to other Chinese athletes bound for the Games in Beijing from August 8 to 24.

The Chinese Swimming Association said in a statement: “The association has made lots of effort on anti-doping. However, this positive test case still happened. It's a big lesson and we need to stay alert.”