UN Secretary-General Antonio Guterres said on Sunday that he strongly condemned the arbitrary detentions of at least 11 UN personnel by the Houthi de facto authorities in Yemen in areas under their control earlier in the day.

In a statement, the UN chief said he further condemned the forced entry into the premises of the World Food Programme, the seizure of UN property, and attempts to enter other UN premises in Sanaa.

Guterres said he strongly reiterated his demand for the immediate and unconditional release of those detained on Sunday, as well as all other personnel from the United Nations, international and national non-governmental organizations, civil society and diplomatic missions who have been arbitrarily detained since June 2024 and those held since 2021 and 2023.

"The continued arbitrary detention of all such persons is intolerable," he said.

He emphasized that the personnel of the United Nations and its partners must never be targeted, arrested or detained while carrying out their duties for the world body, adding that the safety and security of UN personnel and property as well as the inviolability of UN premises must be guaranteed at all times.

"The United Nations will continue to work tirelessly to secure the safe and immediate release of all arbitrarily detained individuals. The United Nations and its partners will continue to support the people of Yemen and their aspirations for a just and lasting peace," the UN chief said.

At least 11 UN staff members were detained on Sunday in Sanaa and Hodeidah, bringing the total number of detained UN staff in northern Yemen to 34, according to UN Special Envoy to Yemen Hans Grundberg.

The Houthis said on Saturday that Ahmed al-Rahawi, prime minister of the Houthi-backed government, and several other ministers were killed in Israeli airstrikes on Sanaa on Thursday while attending a government workshop. The group vowed to retaliate, with Mahdi al-Mashat, head of the Supreme Political Council -- the Houthis' top governing body -- warning in a speech aired by Houthi-run al-Masirah TV that "Israel should await dark days."