Countries should restart development aid for Afghanistan that was halted a year ago when the Islamic Emirate seized power, the UN aid chief said on Monday, as the US told Russia and China to "put your money where your mouth is."

Afghanistan has long relied heavily on development aid, which was cut as the international community demanded the Islamic Emirate respect human rights, particularly for girls and women whose access to work and school has been limited by the interim government.

"Poverty is deepening, the population is still growing, and the de facto authorities have no budget to invest in their own future. It's clear to us that some development support needs to be restarted," UN aid chief Martin Griffiths told the UN Security Council.

More than half of Afghanistan's 39 million people need humanitarian help and six million are at risk of famine, said Griffiths. More than a million children are "estimated to be suffering from the most severe, life-threatening form of malnutrition" and could die without proper treatment, he said.

"Afghanistan's de facto authorities must also do their part. Bureaucratic interferences and procedures slow down humanitarian assistance when it is needed most. Female humanitarian aid workers ... must be allowed to work unhindered and securely. And girls must be allowed to continue their education," he said.

The Islamic Emirate has not been formally recognized by any foreign governments and is still subjected to international sanctions, which the United Nations and aid groups say are now hindering humanitarian operations in Afghanistan.

'PUT YOUR MONEY WHERE YOUR MOUTH IS'

International banks are wary of breaching sanctions and the United Nations and aid groups have been struggling to get enough money into the country over the past year.

"Humanitarians have brought in over $1 billion in cash to sustain program delivery, but the liquidity and banking crisis continues to impact delivery of assistance and on the daily lives of Afghans," Griffiths said.

The United Nations has been trying to kickstart a system - described as a Humanitarian Exchange Facility (HEF) - to swap millions of aid dollars for Afghan currency in a plan to stem aid and economic crises and bypass Islamic Emirate leaders.

Griffiths said this plan was "still under deliberation" with the Islamic Emirate.

Billions of dollars in Afghan central bank reserves, held mainly in the United States, have also been frozen by foreign governments to prevent it from falling into Islamic Emirate hands. Russia and China have called for those funds to be released.

US Ambassador to the United Nations, Linda Thomas-Greenfield, said: "No country that is serious about containing terrorism in Afghanistan would advocate to give the Taliban instantaneous, unconditional access to billions in assets."

The Afghan central bank "was hollowed out long ago" and cannot currently conduct responsible monetary policy, she said, citing a lack of credible systems to combat money laundering and the financing of terrorism.

Thomas-Greenfield said the United States was the top aid donor to Afghanistan and called out Russia and China: "If you want to talk about how Afghanistan needs help, that's fine. But we humbly suggest you put your money where your mouth is."

Russia and China dismissed her remarks.