Yemen's Houthi rebels have detained at least nine Yemeni UN employees, officials belonging to Yemen's internationally recognized government said on Friday.
Others working for aid groups have also been detained, according to authorities.
What do we know about the detentions?
Yemeni officials told the Reuters news agency that three employees of the US-funded National Democratic Institute (NDI) and three employees of a local human rights group were detained alongside the UN staff.
The detained UN employees worked for the world body's human rights office and the office for humanitarian affairs.
Houthi intelligence officers raided the staff members' homes and offices, confiscating phones and computers, the officials said.
The Mayyun Organization for Human Rights condemned the detentions in a statement.
"We condemn in the strongest terms this dangerous escalation, which constitutes a violation of the privileges and immunities of United Nations employees granted to them under international law, and we consider it to be oppressive, totalitarian, blackmailing practices to obtain political and economic gains," the organization said.
Houthi officials did not immediately respond to the allegations.
Who are Yemen's Houthis?
Yemen's Iran-backed Houthi rebels took over the capital, Sanaa, in 2014. They continue to control the city and large swathes of the west of the country.
A Saudi-led coalition has been trying to restore the Yemeni government's rule since 2015.
After the start of the war between Israel and the Gaza-based Hamas militant Islamist group on October 7, the Houthis began attacking international ships in the Red Sea, saying they were acting in solidarity with Palestinians.
The attacks were followed by US and UK strikes targeting the Yemeni rebel group.