Four major non-governmental organisations (NGOs) have halted work in Afghanistan after women were banned from working for them by the Taliban.
In a joint statement, Care International, the Norwegian Refugee Council (NRC) and Save the Children said they would be unable to continue their work "without our female staff".
The aid groups are "demanding" that women can continue to work for them.
Afghanistan's ruling Taliban have been steadily repressing women's rights.
The latest edict on NGOs came just days after the Taliban banned women from attending university.
Taliban ministry of economy spokesperson Abdel Rahman Habib claimed female workers at the foreign aid groups had broken dress codes by not wearing hijabs.
The Taliban threatened to cancel the licence of any organisation that did not swiftly comply with the ban.
The leaders of Care, the NRC and Save the Children said the organisations "would not have jointly reached millions of Afghans in need since August 2021" were it not for their female staff.
"Whilst we gain clarity on this announcement, we are suspending our programmes, demanding that men and women can equally continue our lifesaving assistance in Afghanistan," their statement said.
Separately, the International Rescue Committee (IRC) said in a statement it was suspending its services in the country, citing similar reasons.
IRC said it employs more than 8000 people in Afghanistan, more than 3000 of whom are women.
The suspension of some aid programmes that millions of Afghans access comes at a time when more than half the population relies on humanitarian aid, according to aid agencies, and during the mountainous nation's coldest season.
Earlier, international aid agency AfghanAid said it was immediately suspending operations while it consulted with other organisations, and that other NGOs were taking similar actions.
United Nations top humanitarian coordinator Ramiz Alakbarov said the UN was trying to get the ban reversed and it was a "red line for the entire humanitarian community".
The United Nations could stop humanitarian aid delivery in Afghanistan if the Taliban authorities do not reverse their edict banning women aid workers, the official told the BBC.
But Alakbarov said it was still unclear what the Taliban meant by its edict.
He said the Taliban's minister of health had told the UN the agency should continue its health-related work and women could "report to work and discharge their services".
Other ministries had also contacted the UN directly to say work in the areas of disaster management and emergencies should continue, he said.
Jan Egeland of the NRC said nearly 500 of the aid group's 1400 workers were women, and that female staff had been operating "according to all traditional values, dress code, movement, [and] separation of offices".
He said he hoped the decision would be "reversed in the next few days" and warned that millions would suffer if NGOs' work was obstructed.
NZ Afghan interpreter says difficult for NGOs not to comply
A former Afghan interpreter now living in New Zealand said the ban was devastating and would and stop communities from accessing aid.
Diamond Kazimi worked with the New Zealand Defence Force in Bamiyan as an interpreter for two-and-a-half years, before coming to New Zealand in 2011.
"Without women, they can't achieve human rights towards women, so you've got to have women in those NGOs and international organisations in order to bring equality.
"They tried to ban all women from attending schools and universities, that's including my sister, I've got aunties over there, and now they've just banned them from working for NGOs.
"So they're trying to get some sort of recognition from [the] international community."
The Taliban wanted to be seen as a legitimate government, and leveraging that desire was one way to improve human rights in the region, Kazimi said.
"If you want to have a legitimate government then you need to protect and promote human rights, especially women's rights - you can't take their rights away for education, to have equal employment opportunities, and so on."
However, for the humanitarian organisations involved, it would be difficult and dangerous not to comply with the ban, he said.
Flow-on effects amid 'economic crisis'
NGOs also expressed concern about the effect the ban would have on jobs "in the midst of an enormous economic crisis".
Female Afghan NGO workers acting as the main earners in their household previously told the BBC of their fear and helplessness following the ban.
One asked: "If I cannot go to my job, who can support my family?" Another breadwinner called the news "shocking" and insisted she had complied with the Taliban's strict dress code.
The ban triggered international outcry, with US Secretary of State Antony Blinken warning it would "disrupt vital and life-saving assistance to millions".
Since seizing back control of the country last year, the Taliban has steadily restricted women's rights - despite promising its rule would be softer than the regime seen in the 1990s.
As well as the bans on NGO workers and female university students - in the case of students, now being enforced by armed guards - secondary schools for girls remain closed in most provinces.
Women have also been prevented from entering parks and gyms, among other public places.
-BBC / Reuters / RNZ