“Two journalists on assignment with UNHCR and Afghan nationals working with them have been detained in Kabul,” the United Nations High Commissioner for Refugees agency (UNHCR) said in a tweet.

“We are doing our utmost to resolve the situation, in coordination with others,” it said, adding it would not provide any further information.

The Taliban administration’s security and intelligence agency, the National Directorate of Security, said it had no information on the matter.

“We have no information about them, when and where they have disappeared, we haven’t reached any information yet; we are trying to find information,” said NDS spokesperson Khalil Hamraz, adding the directorate was in touch with the interior ministry about the issue.

There was no indication what prompted the detentions.

U.N. agencies employ journalists to report on their work around the world.

Since the Taliban took over the country in August, concerns have grown over a crackdown on dissent. The U.N. has repeatedly raised alarm over missing women’s rights activists in recent weeks.

Foreign nations have refused to recognise the Taliban-led administration but have ramped up engagement as they try to avert a massive humanitarian crisis stemming from an economy stalled by sanctions and a halt in development funding since the group took over.

A Taliban delegation visited Geneva this week for talks with aid agencies and meetings with Swiss officials. The Swiss Foreign Ministry said it planned to call on the Taliban to respect human rights and international humanitarian law.

(Reporting by Kabul and Islamabad newsrooms Writing by Charlotte Greenfield Editing by Frances Kerry)