The UN human rights chief says her office has received credible allegations of reprisal killings by the Taliban of former Afghan security forces, as well as instances in which officials in the previous government and their relatives were arbitrarily detained and later turned up dead.

Michelle Bachelet, speaking on Monday to the Human Rights Council, warned of a "new and perilous phase" for Afghanistan as she criticised the Taliban for a disconnect between their words and actions.

She cited "multiple" allegations of Taliban house-to-house searches looking for officials from the previous government and "people who cooperated with US security forces and companies".

Such searches took place in at least a half-dozen cities, Ms Bachelet said.

UN staffers have also reported increasing attacks and threats, she added, without providing specifics.

"My office has received credible allegations of reprisal killings of a number of former ANSF (Afghan National Security Forces) personnel, and reports of officials, who worked for previous administrations and their family members being arbitrarily detained," she said.

"In some cases, the officials were released, and in others, they were found dead."

Ms Bachelet also highlighted "deeply troubling information" about Taliban raids on offices of some advocacy groups.

"In contradiction to assurances that the Taliban would uphold women's rights, over the past three weeks women have instead been progressively excluded from the public sphere," she told the 47-member council as it opened its autumn session.

She said girls aged over 12 have been barred from attending school in some places in Afghanistan, and Women's Affairs departments had been at times dismantled.