The UN on Wednesday issued a new call for Yemen’s Houthi rebels to release dozens of aid workers a year after their arrest by the group.

The Iran-backed rebels, who control much of Yemen, detained 13 UN staff members, and more than 50 employees of aid groups last June. Between January 23-25 this year, the Houthis carried out another wave of arrests, detaining an additional eight UN staff members.

Others have been detained since 2021, according to the UN.

Two have died while in detention, one of them a Save the Children staff member and another an employee of the World Food Programme.

“As of today, 23 UN and five international non-governmental organisation personnel remain arbitrarily detained. Tragically, one UN staff member and another from Save the Children have died in detention,” said a statement signed by the UN other top aid groups.

“Others have lost loved ones while being held, denied the chance to attend their funerals or say goodbye,” it added.

The statement said those detained have spent “at least 365 days – and for some, over 1,000 days, isolated from their families, children, husbands, and wives, in flagrant breach of international law.”

“We call on the de facto authorities to deliver on their previous commitments, including those made to the director general of the World Health Organisation during his mission to Sanaa in December 2024,” it said.

The UN and international NGOs will continue to work through all possible channels to secure the safe and immediate release of those arbitrarily detained, it added.

UN Secretary General Antonio Guterres on Tuesday said those detained should have never been attacked by the rebels.

“I renew my call for their immediate and unconditional release,” Mr Guterres said.

“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 said.

Since the arrests were made, the UN has limited its deployments and suspended activities in parts of the country.

At the time of the arrests, the Houthis said an “American-Israeli spy cell” was operating under the cover of aid groups, an accusation firmly rejected by the UN.

Mr Guterres also lamented the “deplorable tragedy” of the death in detention of a World Food Programme staffer in February.

At the time, WFP executive director Cindy McCain said the worker who died in detention was named Ahmed and that he was a “devoted humanitarian and father of two” who had helped deliver life-saving food assistance.

He had been working for the agency since 2017, according to the agency. He was one of seven staffers detained by the Houthi rebels on January 23 this year.

Mrs McCain said she was “heartbroken and outraged by the tragic loss”.

In October 2023, Save the Children confirmed the death of a staff member who died in detention in Yemen and called for an immediate independent investigation.

Safety and security director Hisham Al Hakimi was detained on 9 September while off duty. He died a month and a half later.

Mr Al Hakimi, aged 44 and a husband and father of four, was a dedicated member of the Save the Children family since 2006, the organisation said.