BEIJING, April 25 (Xinhua) -- Nearly all textbooks in China's primary and middle schools are printed in environmentally friendly ways, a ministry expert said Thursday.

Zhang Xiaodan, chief expert of the environmental development center of the Ministry of Ecology and Environment, said the 1.3 billion copies of books were printed using materials and technologies that save energy and leave less environmental footprint.

In places like Beijing, Shanghai and Shaanxi Province, even children's books are increasingly being printed in this manner, Zhang said at a workshop on sustainable consumption and production held at the center.

China has been pushing textbook printing houses to go green since as early as 2010. A set of rules were issued, requiring the use of materials such as pulps, ink and glue that meet strict environmental protection standards.