HAMILTON, Canada 

The US, UK and three allies on Friday condemned the Yemeni Houthi group for recently detaining UN staff.

"We, Australia, Canada, New Zealand, the United Kingdom, and the United States, condemn in the strongest terms the recent detentions by the Houthis of United Nations, diplomatic, and non-governmental organization staff," according to a joint statement.

Expressing support for UN chief Antonio Guterres' demands for the immediate release of all UN staff held by the Houthis, the statement demanded the "immediate and unconditional release of all those detained."

It urged "the Houthis to ensure the safety and security of humanitarian, diplomatic, and United Nations personnel."

"These detentions represent an escalation by the Houthis, and jeopardize a sensitive peace process," it said, adding that the detentions are "an affront to international peace and security."

The five nations affirmed their "strong commitment to the unity, sovereignty, independence, and territorial integrity of Yemen, and our commitment to stand by the people of Yemen."

UN Special Envoy for Yemen Hans Grundberg said Thursday that last week, 13 UN personnel, in addition to five staff members of international NGOs and many more from national NGOs and civil society were arbitrarily detained by the Ansar Allah group.

"I urge Ansar Allah to respect the rights of Yemenis under international law and release all UN and NGO personnel immediately and unconditionally and to refrain from the arbitrary detention of civilians," said Grundberg.

Yemen has been beset by violence and chaos since 2014 when Houthi rebels overran much of the country, including the capital of Sanaa. The crisis escalated in 2015 when a Saudi-led military coalition launched a devastating air campaign aimed at rolling back Houthi territorial gains.

Tens of thousands of Yemenis, including numerous civilians, are believed to have been killed in the conflict, while 14 million are at risk of starvation, according to the UN.