The United Nations on Wednesday started moving up to a third of its international staff out of Afghanistan to Kazakhstan, but stressed the world body is "committed to staying and delivering in support of the Afghan people in their hour of need."

The Taliban seized power on Sunday - 20 years after the Islamist militants were ousted by a U.S.-led invasion for refusing to hand over al Qaeda leader Osama bin Laden in the wake of the Sept. 11, 2001, attacks on the United States.

The United Nations has about 300 international staff and 3,000 national staff in Afghanistan. U.N. spokesman Stephane Durjarric said about 100 of those international staff would be moved to Kazakhstan.

"This is a temporary measure intended to enable the U.N. to keep delivering assistance to the people of Afghanistan with a minimum disruption, while at the same time reducing the risk to U.N. personnel," Dujarric told reporters.

The speed with which the Taliban retook the country, as foreign forces withdrew after a two-decade-long war, has sparked chaotic scenes at the airport in the capital Kabul as diplomats and Afghans try to leave.

Mary Ellen McGroarty, World Food Programme (WFP) director in Afghanistan, said the United Nations was speaking with the Taliban about how the airport would operate once the United States hands over control. She said it was not clear when the United States would leave and what would happen after that.

"The issue will be getting a body similar to the Civil Aviation Authority back in there and the security and control of the airport," she told reporters in New York via video from Kabul. "It's something we're trying to work through with the new authorities to arrive at a workable solution."

"It's going to be a critical lifeline for the humanitarian action in Afghanistan," said McGroarty, adding that the United Nations was currently assessing damage to the civilian side of the airport and two U.N. planes.

The Taliban has promised peaceful rule, saying they would not take revenge against old enemies and would respect the rights of women within the framework of Islamic law.

Caroline Van Buren, representative of the U.N. refugee agency UNHCR in Afghanistan, said there were reports of human rights abuses against women.

"We've been told that in some areas women are not allowed to go to work ... In some areas it's been reported that women are not allowed to move without a male family member," she said, adding that Taliban fighters enforcing this on the ground were "still waiting for instructions from the leadership."

Under Taliban rule between 1996 and 2001, women could not work, girls were not allowed to attend school and women had to cover their face and be accompanied by a male relative if they wanted to venture out of their homes.

Van Buren said there was a "sense of fear and uncertainty among many Afghans" and UNHCR offices around the world were receiving thousands of emails and calls seeking help.