United Nations Secretary-General Antonio Guterres told the Security Council on Wednesday Afghanistan is "hanging by a thread."
The UN chief called for countries to authorize all transactions needed to carry out humanitarian activities in the country.
He also pushed for a suspension of any rules or conditions constricting "lifesaving" aid operations as millions in the country suffer extreme hunger.
"Time is of the essence. Without action, lives will be lost, and despair and extremism will grow. A collapse of the Afghan economy could lead to a massive exodus of people fleeing the country," Guterres said.
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Some $9.5 billion in Afghan central bank reserves remain blocked abroad and international aid has dried up since the Taliban seized power in August.
Donors seek to use the money as leverage over the Taliban on issues including human rights.
The United Nations earlier this month appealed for $4.4 billion in humanitarian aid for Afghanistan in 2022.
On Wednesday, it said it needed a further $3.6 billion for health and education, basic infrastructure, promotion of livelihoods and social cohesion, specifically the needs of women and girls.