Afghanistan's Taliban authorities have detained 18 staff members of a Swiss-registered NGO, including a foreigner, the group said Saturday.

The International Assistance Mission (IAM) said the staffers were picked up from its office in Ghor province, central Afghanistan, and taken to the capital Kabul.

"At this time, we have no information about the nature of allegations against our staff and are, therefore, unable to comment or speculate about this ongoing situation," the group said in a statement issued Saturday.

"However, should any charges be lodged against our organisation or any individual staff member, we will independently review any evidence presented."

Spokesmen for the Taliban authorities were not immediately available for comment.

IAM has operated in Afghanistan since 1966, when it started specialising in eye care but has since branched out into other areas of health and education.

Its website describes the organisation as based on Christian values, but says it does not provide aid according to political or religious belief.

"We value and respect local customs and cultures," the group said in its statement.

An unknown number of foreigners -- including several Westerners -- have been detained by the Taliban authorities since the group's return to power in August 2021.

The Taliban rulers have imposed sweeping restrictions on the population they say are in line with their strict interpretation of Islamic Sharia law -- including barring women from working for NGOs and the United Nations.

Teenage girls and women are also banned from schools and universities, as well as excluded from many other formers of public social life.