Geneva: The UN rights chief voiced grave concern Tuesday at the situation in Afghanistan after the Taliban swept into power, saying their treatment of women would mark a "fundamental red line".

Speaking before an emergency session on Afghanistan, Michelle Bachelet urged the Taliban to honour commitments to respect the rights of women and girls, and ethnic and religious minorities, and refrain from reprisals.

"The onus is now fully on the Taliban to translate these commitments into reality," she said.

"I strongly urge the Taliban to adopt norms of responsive governance and human rights, and to work to re-establish social cohesion and reconciliation, including through respect for the rights of all who have suffered during the decades of conflict," Bachelet told the council.

"A fundamental red line will be the Taliban's treatment of women and girls," she said, urging "respect for their rights to liberty, freedom of movement, education, self expression and employment."