Fast Retailing Co., Asia's biggest clothing retailer, plans to operate 200 Uniqlo stores in mainland China and Hong Kong within five years, with the region set to overtake Japan as its largest sales generator by 2017.

About 80 percent of the stores will be in mainland China, Senior Vice President Tiger Pan Ning said last week. Fast Retailing has five stores in Hong Kong and 10 in mainland China.

The casual clothing chain is tapping the world's fastest growing major economy as sales stall in its home market, which accounts for about 90 percent of total revenue. Fast Retailing's sales from China and Hong Kong will double every year to about 7 billion yuan ($939 million) by 2012, Pan said.

"Sales growth in Japan is very limited as the population is shrinking," Pan, who is also the managing director of the Uniqlo Hong Kong unit, said in a Nov. 2 interview. "The group is shifting focus to Asia, especially to China, as the booming middle class is driving up spending."