The Yemeni government has called on the United Nations to move to second city Aden after Houthi rebels seized its office in the capital Sanaa and detained dozens of staff from international organisations.

"We reiterate the call for the United Nations mission, all UN agencies, international organizations operating in Yemen... to immediately move their headquarters to the interim capital, Aden, and the liberated areas," Information Minister Moammar al-Eryani said on Tuesday on social media platform X.

The Houthis overran the capital Sanaa in 2014 and held most of the country's main population centers, forcing the internationally recognized government to flee to Aden.

A Saudi-led coalition intervened to prop up the beleaguered government the following year.

On Tuesday, the office of the UN High Commissioner for Human Rights said the rebels had entered its Sanaa office on August 3 and forced its staff to hand over the office keys and all its property.

"This serious development comes nearly two months after the wave of kidnappings launched by the Huthi militia," Eryani said, adding it was an escalation of the rebel movement's "repressive measures against international and humanitarian organisations operating in the areas under its control".

In June, the rebels arrested 13 UN personnel, an embassy employee, and more than 50 NGO staff, according to the UN. Two other staff from the UN human rights office were detained in November 2021 and August 2023.

The Houthis said they had arrested members of an "Israeli-American spy ring" operating under the guise of humanitarian organizations. The UN strongly denied the accusation.

Eryani called on the international community to "take strong and deterrent measures commensurate with the crimes committed by the Houthi militia", to pressure them to release the detained staff and to "immediately begin designating the militia as a global terrorist organization".

The war in Yemen has caused hundreds of thousands of deaths and triggered one of the world's worst humanitarian crises. Fighting has significantly decreased since the negotiation of a six-month truce by the UN in April 2022.

Since November, the Houthis have attacked international shipping in the Red Sea and the Gulf of Aden, saying they are acting in solidarity with Gaza.