China's electricity output in June increased around 15 percent from a year earlier, the China Securities Journal reported on Tuesday, citing data from the country's two major grid operators.

The growth rate, if accurate, would be the smallest increase in a non-holiday month since October last year, according to historical data collected by Reuters.

The moderation was partly due to a higher base a year earlier when China's power production rebounded to a positive growth rate, the newspaper report said.

China's monthly power output declined year-on-year from October 2008 to May 2009, as the global economic meltdown hit power consumption.

The country's recent measures to improve energy efficiency, including hiking power prices and reducing tax rebates for energy-intensive firms, have also cut into power demand from sectors such as heavy industry.