The strikes by the Saudi-led coalition on a prison in Houthi territory killed at least 70 detainees, wounded dozens others, and they caused disruption of internet services in the war-torn country.
UN Secretary-General Antonio Guterres has condemned the airstrikes by the Saudi-led coalition on Yemen that left at least 70 dead at a prison and disrupted telecommunications.
Guterres criticised Friday’s attack on the prison in Houthi territory in Saada and the strike on a telecommunications facility that killed at least three children in the port city of Hudaida, according to an aid group.
That attack, Guterres said, knocked out "vital" internet services in the war-torn country.
The Saudi-led coalition denies targeting the detention centre in Saada. It also said the prison hadn't been reported to either the UN or the Red Cross as a site needing to be protected..
However, rescuers said on Friday that at least 70 people were killed in the air strike.
The rebels also released gruesome video footage showing bodies in the rubble and mangled corpses from the attack, which levelled buildings at the prison in their northern heartland of Saada.
Guterres "reminds all parties that attacks directed against civilians and civilian infrastructure are prohibited by international humanitarian law," the UN said in a statement.
"He further reminds all parties of their obligations under international humanitarian law to ensure that civilians are protected against the dangers arising from military operations, adhering to the principles of proportionality, distinction and precaution," it said.
US urges all parties to de-escalate
Meanwhile, US Secretary of State Antony Blinken called for de-escalation in Yemen's long-running conflict after "more than 100 casualties in recent days" including 70 people killed at the prison.
"The United States calls on all parties to the conflict to de-escalate, abide by their obligations under international humanitarian law, and participate fully in an inclusive UN-led peace process," Blinken said in a statement on Friday.
Guterres also condemned the attack by Houthi rebels on Monday on Abu Dhabi which killed three people .
Speaking to reporters after a broad new year address on the global situation to the UN General Assembly, Guterres called the Houthi attack on the United Arab Emirates, a member of the coalition fighting them, "regrettable" and "a serious mistake."
"This escalation needs to stop," he said.
Yemen's civil war began in 2014 when the Houthis descended from their base in Saada to overrun the capital Sanaa, prompting Saudi-led forces to intervene to prop up the government the following year.
Yemen's civil war has been a catastrophe for millions of its citizens who have fled their homes, with many close to famine in what the UN calls the world's worst humanitarian crisis.