Taleban militants in the Swat valley in north-west Pakistan have threatened to kill girls who attend school.
A local Taleban commander ordered parents to stop sending their daughters to school by 15 January.
In comments broadcast on an illegal radio station, he threatened to blow up schools which enrolled female students.
This year alone, Taleban militants have destroyed more than 130 schools in the Swat valley. They want to bring in Islamic sharia law in the region.
Militant attacks on schools in the region have deprived more than 17,000 students of education.
Although schools for girls have come under attack on numerous occasions in the past, this is the first time Taleban militants have issued a complete ban on girls attending them, the BBC's Ethirajan Anbarasan says.
A Taleban spokesman said the prohibition would remain in place unless and until Islamic sharia law was fully implemented in the region.
State-run schools are seen by the insurgents as key symbols of the government.
Now the militants have threatened to destroy private schools as well.
These schools are not Islamic religious institutions and the students are taught courses based on the government syllabus.
Locals say the ongoing attacks on schools have dealt a severe blow to education of girls and young women in the Swat valley.
Those who can afford it have already moved out of the region, but the poor have no other option than keeping their daughters at home, our correspondent says.
Al-Qaeda and Taleban militants are active in the Swat valley, which has been the scene of an insurgency since August 2007.
Hundreds of people have been killed since then in battles between security forces and militants led by Maulana Fazlullah, a cleric with links to the Pakistan Taleban movement.