BEIJING - China's electricity consumption, a common indicator of economic activity, rose 13.7 percent year on year in August, marking its fastest growth since March 2012, according to official data released Saturday.

The figure also marked the fourth straight month of recovery in power use in the world's second-largest economy, according to the National Energy Administration (NEA).

Power consumption expanded to 510.3 billion kwh in August, accelerating from the 8.8-percent increase seen in July and the 3.6-percent growth in August 2012.

In the first eight months, power consumption increased 6.8 percent from the same period last year to 3.5 trillion kwh.

During the same period, electricity use by primary industries totaled 69.2 billion kwh, down 0.5 percent year on year; power consumption by the secondary industry hit almost 2.57 trillion kwh, up 6.3 percent while consumption by the tertiary industry marked the highest rate of growth at 10.7 percent and totaled 416.1 billion kwh.

China added 47.1 gigawatts of power capacity in the January-August period, including 16.05 gigawatts of hydropower and 20.92 gigawatts of thermal power.

The recovery of electric power consumption reflects a firming economy, adding to evidence that the Chinese economy is moving out of the shadow of a protracted slowdown.

A string of economic data, including the Purchasing Managers' Index (PMI), trade, and industrial output all signalled such a trend.

The PMI for the manufacturing sector rose to 51.0 percent in August from 50.3 percent in July, marking the second monthly expansion; exports rose 7.2 percent year on year to 190.61 billion U.S. dollars in August, with ?growth up 2.1 percentage points compared to July; and industrial output grew 10.4 percent year on year last month, up 0.7 percentage points on July.

Ouyang Changyu, deputy secretary-general of the China Electricity Council, said apart from the economic pickup that drove power consumption for August, weather was also an important factor in power use as continuous high temperatures led to an power demand upsurge in south China this summer.

He expected the power use in the third quarter will rebound strongly from that in the second quarter.

The NEA data showed that residential power consumption jumped 21.4 percent year on year to hit 75.7 billion kwh last month, up 9.1 percentage points compared to July.