The World Health Organization on Wednesday warned against interrupting humanitarian aid to Afghanistan which is now under Taliban control, saying the country's fragile health system was vulnerable.

"Sustained access to humanitarian assistance, including essential health services and medical supplies, is a critical lifeline for millions of Afghans, and must not be interrupted," a statement said.

"Months of violence have taken a heavy toll on Afghanistan's fragile health system, which had already been facing shortages in essential supplies amid the Covid-19 pandemic," it added.

The WHO called on "all parties to respect and protect civilians, health workers, patients and health facilities".

It said that between January and July this year, 26 health facilities were attacked and 12 health care workers were killed, making security at such facilities a "major challenge".

Afghanistan fell after a meteoric Taliban offensive, and before the August 31 deadline set by US President Joe Biden for the last American soldiers to pull out.

Many aid donor countries remain on guard about the new regime in the country, where the Taliban ruled with an iron hand from 1996 to 2001.

The United States has said it expects the Taliban to respect human rights, especially those of women.

Germany, Finland and Sweden said on Tuesday that they would stop sending development aid to Afghanistan for now.

Both the International Monetary Fund and the World Bank have remained silent so far, but they could freeze financial assistance to the country.

The WHO statement said it continues to operate in Afghanistan, but noted that in Kabul and other large cities, "there are increasing cases of diarrhoea, malnutrition, high blood pressure, Covid-19-like symptoms and reproductive health complications".

"There is an immediate need to ensure continuity of health services across the country, with a focus on ensuring women have access to female health workers," the world health body said.

On Wednesday the European Union, US and 19 other countries issued a joint statement saying they were "deeply worried about Afghan women and girls".

It was released as concerns soared about the Taliban's return to power after its previous rule prevented Afghan women from working or studying, or travelling without a male "guardian".

"The people of Afghanistan need support and solidarity today more than ever. The gains of the past 20 years cannot be turned back," the WHO added.