CAIRO — Houthis have detained nine United Nations employees in a fresh wave of arrests targeting international organizations, the UN said Monday, raising the total number of detained staff to 53 since 2021.

UN spokesperson Stephane Dujarric said the detentions are part of a “long-running crackdown” that has severely hindered the organization’s ability to deliver life-saving assistance in Houthi-controlled areas.

“The UN calls for the immediate and unconditional release of all UN staff, as well as workers from other international organizations and diplomatic missions who have been detained by the Houthis,” Dujarric said.

“They must be respected and protected in accordance with applicable international law.”

The UN did not specify when or under what circumstances the latest detentions occurred.

Houthi officials have not commented publicly, but the group has previously claimed its arrests target individuals suspected of belonging to an alleged espionage network.

Alessandra Vellucci, chief spokesperson for the UN in Geneva, said all the detained workers are Yemeni nationals.

“Their job is to support their fellow citizens, save lives, provide lifesaving assistance, and they should never be penalized for that or live in fear,” she said.

The detentions mark the latest escalation in the Houthis’ ongoing pressure campaign against international agencies.

In August, the group raided UN offices in Sanaa, detaining 19 employees, including UNICEF’s deputy country director, who was later released.

The crackdown has forced the UN to suspend its operations in the Houthi stronghold of Saada and relocate its top humanitarian coordinator from Sanaa to the coastal city of Aden, which serves as the seat of the internationally recognized Yemeni government.

Yemen’s civil war erupted in 2014 when the Houthis seized Sanaa and much of the country’s north, driving the internationally recognized government into exile. — Agencies