UNITED NATIONS, United States: UN chief Antonio Guterres called Friday for the “immediate and unconditional” release of all humanitarian staff held by Yemen’s Houthis, saying the rebel group had detained seven United Nations workers.
The Iran-backed Houthis have held dozens of workers from the United Nations and other aid groups since the middle of last year, including 13 UN staff since last June.
“Their continued arbitrary detention is unacceptable,” Guterres said in a statement, adding that the “continued targeting of UN personnel and its partners negatively impacts our ability to assist millions of people in need in Yemen.”
“The United Nations will continue to work through all possible channels to secure the safe and immediate release of those arbitrarily detained,” the secretary-general said.
Reeling from a decade of war, Yemen is mired in a humanitarian catastrophe with more than 18 million people needing assistance and protection, according to the United Nations.
The latest detentions of UN staff come after United States President Donald Trump ordered the Houthis placed back on the US list of foreign terrorist organizations.
Re-listing the Houthis will trigger a review of UN agencies and other NGOs working in Yemen that receive US funding, according to the executive order signed on Wednesday.

JERUSALEM: Hundreds of truckloads of aid have entered Gaza since the Israel-Hamas ceasefire began last weekend, but its distribution inside the devastated territory remains an enormous challenge.
The destruction of the infrastructure that previously processed deliveries and the collapse of the structures that used to maintain law and order make the safe delivery of aid to the territory's 2.4 million people a logistical and security nightmare.
In the final months before the ceasefire, the few aid convoys that managed to reach central and northern Gaza were routinely looted, either by desperate civilians or by criminal gangs.
Over the past week, UN officials have reported "minor incidents of looting" but they say they are hopeful that these will cease once the aid surge has worked its way through.
In Rafah, in the far south of Gaza, an AFP cameraman filmed two aid trucks passing down a dirt road lined with bombed out buildings.
At the first sight of the dust cloud kicked up by the convoy, residents began running after it.
Some jumped onto the truck's rear platforms and cut through the packaging to reach the food parcels inside.
UN humanitarian coordinator for the Middle East Muhannad Hadi said: "It's not organised crime. Some kids jump on some trucks trying to take food baskets.
"Hopefully, within a few days, this will all disappear, once the people of Gaza realise that we will have aid enough for everybody."
central Gaza, residents said the aid surge was beginning to have an effect.
"Prices are affordable now," said Hani Abu al-Qambaz, a shopkeeper in Deir el-Balah. For 10 shekels ($2.80), "I can buy a bag of food for my son and I'm happy."
The Gaza spokesperson of the Fatah movement of Palestinian president Mahmud Abbas said that while the humanitarian situation remained "alarming", some food items had become available again.
The needs are enormous, though, particularly in the north, and it may take longer for the aid surge to have an impact in all parts of the territory.
In the hunger-stricken makeshift shelters set up in former schools, bombed-out houses and cemeteries, hundreds of thousands lack even plastic sheeting to protect themselves from winter rains and biting winds, aid workers say.
In northern Gaza, where Israel kept up a major operation right up to the eve of the ceasefire, tens of thousands had had no access to deliveries of food or drinking water for weeks before the ceasefire.
With Hamas's leadership largely eliminated by Israel during the war, Gaza also lacks any political authority for aid agencies to work with.
In recent days, Hamas fighters have begun to resurface on Gaza's streets. But the authority of the Islamist group which ruled the territory for nearly two decades has been severely dented, and no alternative administration is waiting in the wings.
That problem is likely to get worse over the coming week, as Israeli legislation targeting the lead UN aid agency in Gaza takes effect.
Despite repeated pleas from the international community for a rethink, the UN Relief and Works Agency for Palestine Refugees (UNRWA), which has been coordinating aid deliveries into Gaza for decades, will be effectively barred from operating from Tuesday.
UNRWA spokesman Jonathan Fowler warned the effect would be "catastrophic" as other UN agencies lacked the staff and experience on the ground to replace it.
British Foreign Secretary David Lammy warned last week that the Israeli legislation risked undermining the fledgling ceasefire.
Brussels-based think tank the International Crisis Group said the Israeli legislation amounted to "robbing Gaza's residents of their most capable aid provider, with no clear alternative".
Israel claims that a dozen UNRWA employees were involved in the October 2023 attack by Hamas gunmen, which started the Gaza war.
A series of probes, including one led by France's former foreign minister Catherine Colonna, found some "neutrality related issues" at UNRWA but stressed Israel had not provided evidence for its chief allegations.