The Taliban have extended a ban on women working for NGOs to the United Nations' mission throughout the country, a UN spokesman announced Tuesday, calling such an order "unacceptable."

The United Nations Assistance Mission in Afghanistan (UNAMA) had said earlier in the day that UN women employees had been blocked from work in eastern Nangarhar province.

"UNAMA received word of an order by the de facto authorities that bans female national staff members of the United Nations from working," spokesman for the secretary-general, Stephane Dujarric, told reporters, adding that the UN had heard "from various conduits that this applies to the whole country."

The UN had so far been exempt from a December Taliban order for all foreign and domestic NGOs to stop women personnel working across the crisis-stricken nation.

Dujarric said no written order had yet been received, but that the UN was to hold meetings with the Taliban on Wednesday in Kabul to "seek some clarity."

For UN chief Antonio Guterres, Dujarric said, "any such ban would be unacceptable and frankly, inconceivable."

"This is the latest in a disturbing trend undermining the ability of aid organizations to reach those most in need," he added.

After the ban announced last year, several NGOs suspended their entire operations in protest, piling further misery on Afghanistan's 38 million citizens, half of whom are facing hunger according to aid agencies.

After days of discussions, it was agreed women working in the health aid sector would be exempt from the decree, and UN staff, including those in the aid sector, were never beholden to the ban.

Last month, however, UNAMA chief Roza Otunbayeva told the UN Security Council she feared the Taliban government could extend the ban imposed on women working for NGOs to the UN's women staff.

The agency earlier on Tuesday expressed "serious concern that female national UN staff have been prevented from reporting to work in Nangarhar province," in a tweet.

"We remind de facto authorities that United Nations entities cannot operate and deliver life-saving assistance without female staff," it added.

Taliban government spokesman Zabihullah Mujahid told AFP earlier Tuesday he was seeking information on the matter in Nangarhar.

Since surging back to power in August 2021 following the withdrawal of US and NATO troops, the Taliban government has imposed an austere interpretation of Islam.

Authorities have barred teenage girls from secondary school, women have been pushed out of many government jobs, prevented from travelling without a male relative and ordered to cover up outside of the home, ideally with a burqa.

Women have also been banned from universities and not allowed to enter parks or gardens.

UN special rapporteur on human rights in Afghanistan Richard Bennett said in a recent speech in Geneva that the Taliban authorities' policy "may amount to the crime of gender persecution".