"We have been advocating energy saving for years but it has remained only a slogan because of a lack of a supervising system," Beijing vice mayor Zhang Hao was quoted as saying.

The "energy police", as Zhang called them, would be authorised to fine owners of buildings that used too much power, adding teeth to city orders to improve energy efficiency that carried no penalties, the newspaper said.

China has struggled to generate enough power to keep up with its breakneck economic growth, about 9 percent annually, and has faced severe energy crunches the past two summers.