The United Nations said Yemen's Houthis detained at least 11 workers on Sunday in raids on U.N. premises, after rebel authorities made numerous arrests following Israel's killing of their prime minister.

The Houthi authorities have not yet commented on the reported raids, but the group has previously arrested international aid workers.

U.N. Secretary-General Antonio Guterres called for their "immediate and unconditional release," confirming that 11 U.N. personnel had been subjected to "arbitrary detentions ... by the Houthi de facto authorities."