The Taliban government is purging books written by women from Afghanistan’s male-only university system and outlawing gender studies courses, the latest blows in a campaign against women’s rights since the group returned to power four years ago.

Over 600 books, many of them written by women, were included in a 50-page list of banned works. The directive was announced in a letter to universities by the Taliban’s deputy higher education minister, dated to late August, and published by the Independent Persian on Thursday. The letter said the titles were in conflict with principles of Sharia, or Islamic law.

A member of the committee reviewing the books later clarified the Taliban’s position to BBC Afghan, that “all books authored by women are not allowed to be taught.”

The ban is “a criminal act,” said Rahela Sidiqi, the director of The Rahela Trust, a Britain-based group that works in Afghanistan to help women and girls access education. “It not only affects females. It also affects males. It affects society, because those books were part of the curriculums of those universities.”

Alongside the book ban, the Taliban has instructed universities to drop 18 courses spanning topics from human rights and democracy to women’s studies, and said more than 200 others were under review.

“We know in the spring, there was a committee put together by the Ministry of Higher Education to do exactly this,” said Lauryn Oates, the executive director of Right to Learn Afghanistan, a group based in Canada that supports human rights and education for girls and women in Afghanistan. “This will give people the false idea that women don’t write books, or that women’s ideas are not worth consulting.”