Dissatisfied by a thin pad of prescriptions offered by an employee at a west Beijing chemist's, Wang Zhexiong demanded more to check whether rules were being followed in the selling of medicine containing performance-enhancing substances.

The call of Wang, deputy head of drug safety with China's State Food and Drug Administration (SFDA), is part of China's more aggressive anti-doping efforts ahead of the Olympics.

In the latest move senior officials, including Wang, from the central government were sent to Beijing, Shanghai, Tianjin and 12 provincial areas for anti-doping inspections. The 12-day campaign is to last till July 7.

The inspectors were dispatched by seven ministry-level government agencies, including drug safety, health and public security watchdogs, and the Beijing Organizing Committee for the Olympic Games (BOCOG).

Every link, from drug producers and chemical plants to medicine wholesalers and retailers, would be checked through spot checks, both announced and covert.

"We must ensure nothing goes wrong with any of these links, especially over the counters," said Wang. "So that as few chances as possible are left for doping drug misuse, unintentional or intentional, by athletes."