Afghan women are being cut off from crucial aid because of a growing Taliban crackdown in areas controlled by the insurgents, more than a dozen relief workers have told AFP.

The militants have demanded an end to projects helping women to be more independent and have barred female staff from entering their territory in some areas.

"So far the hypothesis is that the Taliban have changed, but this is really a concrete example that they haven't," said one aid worker who did not want to be named.

Washington recently lambasted the insurgents for failing to abide by a landmark deal last year that committed them to honouring a number of security guarantees. 

The agreement also called for the withdrawal of foreign troops by May and paved the way for peace talks between the Taliban and the Afghan government. 

The deal initially raised hopes the insurgents were open to moderating some of their hardline positions. 

But people working in pockets of territory under Taliban control, primarily in northern Afghanistan, say conditions in some areas deteriorated after the US accord was signed.

- 'They're not joking at all' -

Fears are growing that the Taliban are waiting for the Americans to leave before attempting to retake the country by force and reintroduce their draconian vision for Afghan society. 

The group ruthlessly oppressed women during their brief rule over the country in the 1990s, banning them from working outside the home and subjecting them to violent punishments for perceived infractions.

The jihadists have since made vague pledges to protect women's rights in Afghanistan.

In an open letter published last month, Taliban co-founder Mullah Abdul Ghani Baradar said the group was "committed to upholding and guaranteeing all rights of women afforded to them by Islamic law".

But on the ground, aid groups say the group are as uncompromising as ever. 

Some say their work is unravelling after years of building up delicate relationships with the insurgents to reach impoverished Afghan women and girls.

In a letter addressed to aid groups, the Taliban warned it was unacceptable for them to "take women out of their homes in the name of women's economic empowerment, education and sports programs".

Pressure against these kinds of programmes are not new, but are becoming "a lot more official and widespread", a senior humanitarian aid manager said. 

"When you receive a letter from the Taliban, they're not joking at all, you have to apply it," said another official working with an international aid group.

After nearly 40 years of conflict, Afghanistan is almost entirely reliant on international aid and the Taliban appear set on bringing humanitarian workers to heel.

"Aid workers and the relief they provide seem to have fallen in the crosshairs of the Taliban's attempts to portray themselves as a governing entity," said International Crisis Group analyst Andrew Watkins.

- 'We take blood on our hands' -

Afghan women working with aid groups who once regularly travelled to insurgent-held enclaves in the north say they have been blocked by the Taliban from entering certain areas to work.

"We tried a lot to convince them but they said no, not having women," one aid worker told AFP.

Another group said they had been forced to send only male staff to oversee certain projects in Taliban areas.

A staff member from that organisation said it decided to not recruit women to work on a new aid project as a result. 

"They said they won't have access so there's no point of having someone sit in the office," said the staff member who was working for the organisation.

In areas where the Taliban are more flexible, Afghan women aid workers are required to wear burqas, must be accompanied by a male chaperone from their family and have to watch what they say.

"We do not use the terms 'human rights' or 'women's rights' because they are sensitive words," said one aid worker.

Others say travel has become increasingly dangerous and they risk getting caught in firefights, with the Taliban engaged in fierce battles with Afghan security forces over territory.

"When we travel, we take blood on our hands," another aid worker told AFP. "Because we are usually (caught) in crossfire."