Yemenis search for survivors after an airstrike by the Saudi-led coalition in the old city of Sana’a, a Unesco World Heritage Site, in Yemen on 12 June 2015. (Photo: EPA / Yahya Arhab) 
U.N. Secretary-General Antonio Guterres said the Houthis forcibly entered World Food Programme premises, seized U.N. property and attempted to enter other U.N. offices in the capital.
The raid followed an Israeli strike on Sanaa on Thursday that killed the prime minister of Yemen's Houthi-run government and several other ministers.
U.N. Special Envoy for Yemen Hans Grundberg said in a separate statement that the 11 staff were detained in both Sanaa and the port city of Hodeidah.
UNICEF, the U.N. Development Programme and the office of the U.N. High Commissioner for Refugees are among other U.N. agencies with offices in one or both of the two cities.
Grundberg said the detentions were in addition to 23 other U.N. staff previously detained, some since 2021, and one who died in detention this year.
(Reporting by Michelle Nichols, Mohammed Ghobari, Yazhini MV and Rhea Rose Abraham; Editing by Cynthia Osterman and Diane Craft)