“The Secretary-General strongly condemns the continued arbitrary detentions of its personnel and its partners, as well as the ongoing unlawful seizure of UN premises and assets in areas under Houthi control,” his Spokesman Stéphane Dujarric said in a statement on Monday.

“These actions hinder the UN’s ability to operate in Yemen and to deliver critical assistance.”

The statement did not provide details on the latest detentions.

Dozens being held

The Houthis, formally known as the Ansar Allah movement, have been battling with Yemen’s internationally recognized Government for more than a decade.

The rebels control large areas of the country, including the capital, Sana’a, and have been targeting humanitarians.

In addition to the UN staff, they are holding personnel from international and national non-governmental organizations (NGOs), civil society and diplomatic missions, all of whom are Yemeni nationals.

Since the start of the war in Gaza, now in its third year, the Houthis have been attacking Israeli and other commercial ships in the Red Sea in what they say is a show of solidarity with the Palestinian people. They have also launched drone and missile strikes against Israel.

Release all detained personnel

The Secretary-General renewed his urgent call for the immediate and unconditional release of all the UN and other personnel being detained, saying they must be respected and protected in accordance with international law.

He reiterated that UN personnel must be allowed to work without hindrance, and that UN premises and assets are inviolable and must be protected at all times.

“The United Nations will continue to work tirelessly, and through all available channels, to secure the safe and immediate release of all arbitrarily detained personnel, as well as the return of UN agency offices and other assets,” said Mr. Dujarric.

“The Secretary-General remains steadfast in the UN commitment to support the people of Yemen and their aspirations for a just and lasting peace.”