China, the world's second-largest economy after the U.S., devalued its currency last month in a bid to help exporters. The country is grappling with a softening economy and wild swings in the stock market.
"Having achieved a 3 percent move in a few weeks, they would not want to stop here. Their ultimate target is probably a 15 to 20 percent minimum move in the trade-weighted index," IDEAglobal cited the source as saying in an interview.
The yuan was trading at about 6.3708 per dollar on Wednesday, having weakened to four year-low around 6.45 after last month's surprise devaluation.