China will establish an accountability mechanism for textbooks used by students at all levels to ensure quality and standardization, according to a new guideline released on Monday.

The guideline, issued by the Ministry of Education and four other departments, stressed that the accountability mechanism will cover compiling, vetting, printing, distribution and selection of textbooks.

Local governments and schools should make sure all relevant institutions and individuals understand their responsibilities in ensuring the safety of textbooks.

The accountability mechanism also applies to digital textbooks, textbook materials used by teachers and translated textbooks used by ethnic groups.

Authorities in the Xinjiang Uygur autonomous region caught a separatist group that incorporated ethnic separatism, violence, terrorism and religious extremism content into minority-language textbooks, according to Wang Langtao, vice-president of the Xinjiang regional high court.

The group, led by Sattar Sawut, former director of the Xinjiang regional education department, preached ethnic separatism, violence, terrorism and religious extremism in the 2003 and 2009 editions of the textbooks, Wang said at a news conference in March.

These textbooks were used for 13 years by 2.32 million Uygur students, leading to grave consequences, he said.

Several of the convicted people who took part in the terrorist attacks in Urumqi in July 2009 and April 2014 were influenced by these textbooks, he said.

Sattar Sawut was sentenced to death with a two-year reprieve after being found guilty of crimes of separatism and taking bribes of 15 million yuan ($2.3 million). He did not appeal the verdict, according to Wang.

There have also been reports of textbooks containing advertisements. In 2017, netizens found that a Chinese textbook used by high school students contained a link to a pornographic website.

The publisher of the textbook, People's Education Press, said the link originally led to a website of poems and essays, but the website had been changed.

Tian Huisheng, director of the Ministry of Education's department of national textbooks, said the ministry has issued textbook management guidelines for primary and secondary schools, vocational schools, universities and foreign textbooks.

These guidelines outline detailed requirements on compiling, adaptation and usage, he said at a news conference.

Management plans for digital textbooks, minority-language textbooks, extracurricular training materials and reading materials have also been issued.

All people responsible for textbook compilation, review and selection must be vetted thoroughly to prevent any textbooks with unscientific content and wrong values entering students' backpacks, he said.

The country has more than 5,000 experts who work on compiling and reviewing textbooks, and more than 3,000 experts responsible for vetting textbooks, Tian said.

As of the end of 2020, the country had almost 190,000 types of textbooks covering all stages of education.