China's energy use rose at the fastest pace in four years in 2011 while efficiency improved, according to the National Bureau of Statistics.

Consumption climbed 7 percent to 3.48 billion metric tons of standard coal equivalent, a report on the bureau's website showed on Wednesday. That was the fastest rate since 2007, when it grew 7.8 percent, according to data compiled by Bloomberg.

Consumption for each unit of GDP, or energy intensity, fell 2.01 percent from 2010, the statistics bureau said.

The data underscore China's increasing share of world energy demand even as the nation attempts to curb the cost of powering its factories and reduce pollution. The government wants to cut energy intensity by 16 percent in the five years through 2015.

"The nation's energy use has been supported by strong coal demand," Aochao Wang, head of China research at UOB-Kay Hian Ltd, said by telephone from Shanghai. "The increased use of coal constrains the nation's efforts in improving energy efficiency."

Demand for coal, which China relies on for about 70 percent of its energy needs, rose 9.7 percent year-on-year in 2011, the report said, without giving absolute volumes. That was the highest growth rate since 2005.

Crude oil use increased 2.7 percent and natural gas gained 12 percent, it said.

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