BEIJING (REUTERS) - China will investigate claims that virtually all the raw materials used to produce illegal performance-enhancing drugs come from the country, even if they have serious reservations about their accuracy, state media said on Tuesday.

World Anti-Doping Agency (WADA) director general David Howman told Reuters in an interview last week that "ninety-nine percent" of the materials used by criminal gangs around the world to make the drugs were emanating from China.

"We are shocked at Mr Howman's comment," Jiang Zhixue, the head of anti-doping at China's sports ministry, told the official Xinhua news agency.

"We are wondering where this 99 percent came from and what is his evidence. We have asked for a more detailed explanation from WADA."

Jiang said the probe would require coordination from various ministries as had happened in a crackdown on the manufacture and sale of banned performance-enhancing substances in the run-up to the 2008 Beijing Olympics.

China's record on doping at elite levels of sport improved markedly after Beijing won the right to hold the 2008 Games, a far cry from the 1990s when the country's rise to sporting superpower was accompanied by regular scandals.