UNITED NATIONS - UN Secretary-General Antonio Guterres on Wednesday condemned the continued arbitrary detention of UN personnel by the Houthis in Yemen.

"I strongly condemn the continued arbitrary detention of 59 UN colleagues and partner personnel, as well as staff from NGOs, civil society organizations, and diplomatic missions," he told reporters after briefing the Security Council on the situation in Yemen in closed-door consultations. "I call for their immediate and unconditional release, in accordance with international law."

In recent days, Houthi de facto authorities referred three UN personnel to a special criminal court. This referral must be rescinded, Guterres said. They have been charged in relation to their performance of UN official duties. These charges must be dropped, he said.

"The continued detention of our colleagues is a profound injustice to all those who have dedicated their lives to helping the people of Yemen. The United Nations and its partners must never be targeted, arrested, or detained in connection with their official duties. We must be allowed to perform our work without interference," said Guterres.

In the press encounter, Guterres called for de-escalation of the tensions in Yemen.

Tensions have been simmering across Yemen, and dramatic new developments in the eastern governorates are turning up the heat, he said. "A full resumption of hostilities could have serious ramifications on regional peace and security, including on the Red Sea, in the Gulf of Aden, and in the Horn of Africa."

Guterres urged all parties to exercise maximum restraint, de-escalate tensions, and resolve differences through dialogue.

"Yemen needs a sustainable, negotiated political settlement -- one that embraces the aspirations of all Yemenis and brings this devastating conflict to an end. Until then, the Yemeni people will continue to pay a terrible price," he said.