UN Secretary General Antonio Guterres has called for the immediate and unconditional release of 11 UN staff arrested by Houthi authorities in Yemen.

The workers were detained by security forces in raids on the World Food Programme (WFP), children's charity Unicef, and the World Health Organization (WHO), news agencies and the UN said. Sunday’s raids took place in the capital, Sanaa, and port city of Hudaydah, UN Special Envoy for Yemen Hans Grundberg stated.

Grundberg noted that the Houthis had already been holding 23 other UN workers arrested since 2021. Houthi authorities have not commented on Sunday’s arrests.

In a statement, Guterres expressed his strong condemnation of the arbitrary detentions, also criticizing the forced entry into UN premises and the seizure of property. It remains unclear why the Houthis targeted UN workers, who have played a crucial role in providing aid to civilians suffering in one of the world’s worst humanitarian crises.

One detainee reportedly died in custody earlier this year, while approximately 20 Yemeni employees of the US embassy have been held for the past three years. Grundberg highlighted that despite continued international engagement over the last year, such arbitrary detentions persist, significantly hindering efforts to deliver assistance and promote peace in Yemen.

The latest arrests come amidst heightened tensions following an Israeli airstrike that killed the Houthi prime minister and other officials. This strikes a crucial blow to the Houthis, who have been targeting Israel since November 2023 amid ongoing conflict related to the Gaza Strip.

The Iran-backed Houthis have been in control of Yemen’s capital and north-western region since ousting the internationally recognized government during a civil war in 2015. This conflict has resulted in over 150,000 deaths, with millions displaced and in urgent need of aid.