HONG KONG - China's inflation accelerated to the fastest pace in three years, highlighting the challenge for policy makers of sustaining growth while taming prices.

The consumer price index increased 6.4 percent in June, the National Bureau of Statistics (NBS) said on Saturday, exceeding the 6.2 percent median estimate of economists surveyed by Bloomberg News.

The world's second-biggest economy is already cooling after the government curbed lending by boosting lenders' reserve requirements to a record and raising interest rates five times since September, most recently on July 6. A deeper-than-anticipated slowdown in China would curtail a global expansion imperiled by a potential default by Greece and signs the US recovery is faltering.