The head of the United Nations Afghanistan aid operation expressed strong concerns Tuesday over military gains by the Taliban insurgents as US and coalition forces pull out of the country.

"All of the major trends -- politics, security, the peace process, the economy, the humanitarian emergency, and Covid -- all of these trends are negative or stagnant," Deborah Lyons told the UN Security Council in a video conference.

"The Taliban's recent advances are even more significant and are a result of an intensified military campaign," said Lyons, who leads the UN Assistance Mission in Afghanistan.

"For the Taliban to continue this intensive military campaign would be a tragic course of action," she said.

She said the Islamist insurgents have seized more that 50 of the country's 370 districts, mostly districts which surround provincial capitals.

That, Lyons said, suggests the Taliban "are positioning themselves to try and take these capitals once foreign forces are fully withdrawn."

She said if the insurgents continue their fight, the prolonged violence "would extend the suffering of the Afghan people and threaten to destroy much of what has been built and hard won in the past 20 years."

She expressed special worries for the rights of women as the ultra-conservative Taliban gain ground.

"Preserving the rights of women remains a paramount concern and must not be used as a bargaining chip at the negotiating table," she said.

In the same forum, the US ambassador to the United Nations, Linda Thomas-Greenfield, stressed that the world would not accept the Taliban seizing control of Kabul and the government.

"The world will not recognize the establishment in Afghanistan of any government imposed by force, nor the restoration of the Islamic Emirate," Thomas-Greenfield said.

"There is only one way forward: a negotiated and inclusive political settlement through an Afghan-led and Afghan-owned process. "