The (A)H1N1 flu will endanger more lives in the coming months as it spreads across the globe, and governments have to prepare for a swift response, a senior WHO official said on Friday.

H1N1 flu cases could double every three to four days for several months until they reached the peak transmission period, Shin Young-soo, WHO Western Pacific director, said.

At one point, there could be an explosion of cases, Shin told a symposium of health officials and experts in Beijing. "It is certain there will be more cases and more deaths."