Bangladesh said Saturday it had withdrawn two new school textbooks after protests from Islamist groups incensed by a curriculum overhaul to recognise transgender identities, same-sex relationships and secular science.

Thousands have demonstrated in the capital Dhaka since last month demanding that the National Curriculum and Textbook Board (NCTB) scrap the changes to the books, published for students aged 11 to 13.

One section of the new history and social science book narrates the story of a child called Sharif who transitions, takes the female name Sharifa and goes to live with other transgender people.

The state-run NCTB said it took the decision to withdraw the books "due to some criticisms and to reduce reading load on students".

"Many schools in our rural areas don't have adequate resources to impart lessons from these books and the contents are a little heavy," spokesman Mohammad Mashiuzzaman told AFP.

"There are also debates over the contents of the books. So we decided to take them out for now so that no one can politicise the issue."

In 2014, the Bangladeshi government allowed people to identify themselves as belonging to a third gender, and it has in recent years given "hijras" broader rights in areas such as housing and higher education.

Multiple Islamic clerics have even issued decrees declaring them part of the country's Muslim mainstream.

Several trans people have contested and won local elections.

But the conservative Muslim-majority country's roughly 1.5 million transgender people still face discrimination and violence, and are often forced into begging or the sex trade to earn money.

The NCTB will also modify the content of two other books, Mashiuzzaman said, referring to titles that Islamist groups claimed were "promoting homosexuality", distorting Bangladeshi history and criticising the tradition of veil-wearing by Muslim women.

One of the withdrawn books included the theory of evolution pioneered by British naturalist Charles Darwin. The book enraged Islamist groups, who called the theory dangerous and demanded it be dropped from the curriculum.