The United Nations has called for an urgent investigation into the death of a staff member held in Houthi detention in Yemen, with senior UN officials expressing outrage and demanding full transparency from the armed group.

Mohammad el-Shami, a staff member of the Office of the United Nations High Commissioner for Human Rights (OHCHR) in Yemen, died in custody after being arbitrarily held for more than a year. He had been detained since June 2024, when he and more than 60 people working with the UN and other non-governmental organisations were arrested and accused of being part of an "American-Israeli spy network."

El-Shami died more than a month ago, but his family was only recently informed, the UN said in a statement on Saturday. The Houthis did not disclose how he died.

UN High Commissioner for Human Rights Volker Turk said el-Shami's family "deserve to know the truth" and demanded "full transparency" from the Houthi authorities, as well as an "urgent, independent and thorough investigation" into the circumstances of his death.

Turk also said he was "gravely concerned" for seven other OHCHR personnel detained alongside el-Shami who remain in custody. "I appeal again for their immediate and unconditional release," he said.

UN Secretary-General Antonio Guterres said in a separate statement on Saturday that he was "appalled" by el-Shami's death and echoed calls for a full investigation. The UN is "urgently seeking answers" from the group about the circumstances of his death, Guterres added.

El-Shami is the second UN staff member to die in Houthi detention. A World Food Programme staffer died in February 2025 under similar circumstances.

A total of 72 UN staffers and NGO workers, including el-Shami, have been detained by the Houthis since the wave of arrests began in June 2024. The UN paused operations in parts of Houthi-held Yemen in February 2025 over concerns for the safety of its employees.

The rebel group has previously paraded some detainees on television, presenting them as collaborators with Western intelligence agencies and Israel. On October 6, the UN announced that one World Food Programme employee had been released after being "arbitrarily detained" by the Iran-backed group.