The gap between drug cheats in sport and those chasing them down is narrowing, said World Anti-Doping Agency's director general David Howman.

"It's always difficult to say how it will evolve," Howman told a press conference Wednesday in Doha.

"The gap is narrowing. Battles in the war over doping are being won," he added.

Howman is heading a WADA inspection team to monitor the doping control at the 15th Asian Games in the Qatari capital.

"Sport cannot do everything. We need governments to use enforcement agencies and enforce the sanctions against the cheats," said Howman, a 58-year-old New Zealander.

"It is a case of increasing research and intelligence gathering on athletes we suspect are cheating."

Howman mentioned several examples of where law enforcement agencies had helped the war on the cheats, including the French Government over the Cofidis trial (another cycling scandal involving a French team) and the US Government over the BALCO scandal (a California-based laboratory which supplied illegal substances to baseball players and leading athletes).