United Nations Secretary-General Antonio Guterres on Tuesday demanded Yemen's Houthis to release dozens of aid workers, including UN staff, a year after their arrest.
The Iran-backed Houthis, who control much of the war-torn country, detained 13 UN personnel and more than 50 employees of aid groups last June, AFP reported.
"I renew my call for their immediate and unconditional release," Guterres said in a statement issued by the office of his special envoy for Yemen, Hans Grundberg.
"The UN and its humanitarian partners should never be targeted, arrested or detained while carrying out their mandates for the benefit of the people they serve," he added.
The Houthis at the time claimed an "American-Israeli spy cell" was operating under the cover of aid groups -- an accusation firmly rejected by the UN.
Guterres also lamented the "deplorable tragedy" of the death in detention of a World Food Program staffer in February.