The Taliban must uphold the fundamental human rights of women and children, the United Nations chief said Wednesday, urging the international community to release frozen Afghan aid to prevent families from selling their babies to buy food.

Secretary-General Antonio Guterres also warned that "Afghanistan is hanging by a thread" as millions of impoverished citizens struggle to survive amid deteriorating humanitarian conditions.

"We urge the Taliban to seize this moment and garner international trust and goodwill by recognizing -- and upholding -- the basic human rights that belong to every girl and woman," Guterres told a UN Security Council meeting.

He expressed concern about recent reports of arbitrary arrests and abductions of women activists, saying: "I strongly appeal for their release."

At the same time, he added, "I appeal to the international community to step up support for the people of Afghanistan," including by releasing aid funds in Washington that remain frozen by the World Bank and the US government.

Over half of all Afghans face "extreme levels of hunger," Guterres told the council, and "some families are selling their babies to purchase food."

China's UN ambassador Zhang Jun mentioned the case of one woman who "sold her two daughters and a kidney" to feed her family.

"This is a human tragedy", he said, implicitly urging Washington to lift "unilateral sanctions" and ease the freeze on Afghan assets.

The United Nations continues to call for "a relaxation of those sanctions" which squeeze the economy and prevent the full delivery of essential services, UN envoy to Afghanistan Deborah Lyons told the council via videolink.

Guterres said international aid agencies and donors "need to jump-start Afghanistan's economy through increased liquidity," including $1.2 billion from a World Bank-managed fund for Afghanistan's reconstruction that has been frozen since the fundamentalist Taliban took over last August when US forces exited.

"Without action, lives will be lost, and despair and extremism will grow," he said.

Taliban officials recently held talks with Western powers in Oslo to address the humanitarian crisis, with Western diplomats linking humanitarian aid to Afghanistan to an improvement in human rights.

Led by Norwegian Prime Minister Jonas Gahr Store, whose country currently chairs the Security Council, Wednesday's session of the 15-member body sought to clarify the mandate of the UN political mission in Afghanistan.

The mandate expires March 17 and must be reviewed to account for the Taliban's return to power.