An anti-doping agency suspects genetic engineering technology is being used by some Olympic athletes to boost their performance.
Drug Free Sport New Zealand says agencies suspect that some athletes at the Beijing Olympics in 2008 used gene doping and can't rule out the possibility it will be used again in London.
Genetic scientists at Otago University say that while animal trials have shown genetic engineering can dramatically boost athletic performance, the side effects are poorly understood.
They say treatments currently available are untested, and potentially unsafe.
