The Taliban on Friday urged Washington to heed a call by the United Nations chief to unlock Afghan funds frozen in the United States, as a humanitarian crisis deepens.

US authorities froze billions of dollars in Afghan assets after the hardline Islamists seized power in August following the withdrawal of foreign forces.

On Thursday, UN Secretary-General Antonio Guterres called on Washington to take the lead and prevent "the nightmare unfolding in Afghanistan" by releasing capital.

"The United States must respond positively to the international voice and release Afghan capital," the Taliban government's spokesman Zabihullah Mujahid said on Twitter.

Washington has taken control of nearly $9.5 billion in assets belonging to the Afghan central bank.

The International Monetary Fund and World Bank have suspended activities in Afghanistan, withholding aid as well as $340 million in new reserves issued by the IMF in August.

Many Western nations have also largely suspended their assistance to Afghanistan, one of the world's poorest countries.

Aid agencies and the UN have estimated that more than half of the nation's 38 million population is expected to face hunger this winter.

"We must... rapidly inject liquidity into the economy and avoid a meltdown that would lead to poverty, hunger and destitution for millions," Guterres told reporters in New York.

His comments came two days after the UN said it needs $5 billion in aid for Afghanistan in 2022.