JINAN - Hundreds of factories in East China's Shandong province will remain closed in the winter to curb production, according to a government notice.

Shandong Economic and Information Technology Committee, the government agency in charge of industries in China's third-largest provincial economy, published shutdown periods and the factories' names, including those owned by Hong Kong-listed China Hongqiao Group, China Shanshui Cement and China National Building Material.

Among the Shandong-based factories closed or with restricted production are the aluminum and aluminum oxide production lines of China Hongqiao, the world's leading aluminum product manufacturer, in the city of Binzhou.

Production at many cement factories of China Shanshui Cement and China National Building Material was also suspended or limited.

The shutdown periods vary from two to four months.

Clean air targets are particularly difficult to meet in winter for provinces and municipalities in north China, when residential heating systems are switched on starting mid-November, adding pressure to air quality.

Government authorities, including those in neighboring municipalities and provinces such as Beijing, Tianjin and Hebei, have resorted to temporary shutdowns of factories to reduce pollution.