HONG KONG  Earlier this summer, Prime Minister Wen Jiabao of China promised to use an “iron hand” to improve his country’s energy efficiency, and a growing number of businesses are now discovering that it feels like a fist.

The Ministry of Industry and Information Technology quietly published a list late Sunday of 2,087 steel mills, cement works and other energy-intensive factories required to close by Sept. 30.

Energy analysts described it as a significant step toward the country’s energy-efficiency goals, but not enough by itself to achieve them.

Over the years, provincial and municipal officials have sometimes tried to block Beijing’s attempts to close aging factories in their jurisdictions.