The Saudi-led coalition has denied reports that it bombed a prison in the northern Yemeni city of Saada, as the United Nations condemned the deadly coalition air strikes in the country.

An official from Yemen’s Houthi rebel group and medical charity Doctors Without Borders (Medecins Sans Frontieres, or MSF) said on Friday that dozens of people were killed in a dawn bombing of a temporary detention centre in the northern city.

The Houthis released footage showing rescue workers pulling bodies from the rubble, and Taha al-Motawakel, health minister in the Houthi government that controls the country’s north, told The Associated Press news agency that 70 detainees had been killed.

Al-Motawakel accused the Saudi-led coalition of deliberately targeting civilians.

“We consider this a war crime against humanity. The world should take responsibility at this critical moment in human history,” he said.

An MSF spokesperson told the AFP news agency the death toll was at least 70 and that 138 others had been wounded.

The Saudi-led coalition denied it carried out the strike.

“The coalition will inform the Office for the Coordination of Humanitarian Affairs (OCHA) in Yemen and the International Committee of the Red Cross (ICRC) on the facts and details,” the official SPA news agency said on Saturday, citing a coalition spokesman.

He said the target in Saada was not on no-targeting lists agreed upon with the OCHA, was not reported by the ICRC and did not meet the standards stipulated by the third Geneva Convention (Geneva Convention Relative to the Treatment of Prisoners of War).

Al-Malki said the coalition would share with both agencies “the facts and details, as well as the media misinformation” by the Houthis about the facility.

Eight aid agencies operating in Yemen said in a joint statement they were “horrified by the news that more than 70 people, including migrants, women and children, have been killed… in a blatant disregard for civilian lives”.

They said the prison in Saada was used as a holding centre for migrants, who made up many of the casualties.

Intensified aerial bombing

During the past week, the coalition has intensified aerial bombing on what it has said are military targets linked to the Houthis, after the group carried out unprecedented drone attacks on the United Arab Emirates (UAE), which is part of the coalition, on Monday. The Yemeni group fighting the Saudi-led coalition has also been behind cross-border missile and drone attacks in Saudi Arabia.

On Tuesday, at least 14 people were killed after the coalition carried out air strikes in the capital Sanaa.

Further south in the port city of Hodeida, at least three children were killed when air strikes by the Saudi-led coalition hit a telecommunications facility as they played nearby, Save the Children said. Yemen also suffered a country-wide internet blackout.

“The children were reportedly playing on a nearby football field when missiles struck,” Save the Children said.

The coalition claimed the attack in Hodeida, a lifeline port for the war-torn country.

UN condemns air raids

US Secretary of State Antony Blinken said in a separate statement that the heightening of the conflict was of “great concern” to the United States and called on all sides to de-escalate.

He earlier spoke to Saudi Foreign Minister Faisal bin Farhan Al Saud to reaffirm a US commitment to help Gulf allies improve their defence, and stressed “the importance of mitigating civilian harm,” the Department of State said.

UN Secretary-General Antonio Guterres condemned air strikes by a Saudi-led coalition on Friday.

“The Secretary-General calls for prompt, effective and transparent investigations into these incidents to ensure accountability,” Guterres’ spokesman, Stephane Dujarric, said.

The UN chief reminded “all parties that attacks directed against civilians and civilian infrastructure are prohibited by international humanitarian law”.

Meanwhile, on Friday, the United Nations Security Council condemned the attack on the UAE and other sites in Saudi Arabia after a closed-door meeting that was requested by the UAE.

Tensions have soared in recent weeks after the UAE-backed Giants Brigade drove the Houthi rebels out of southern Shabwa province, undermining their months-long campaign to take the key city of Marib further north.

On January 3, the Houthis hijacked a UAE-flagged ship in the Red Sea, saying the vessel carried weapons.

The Saudi-led coalition’s 2015 intervention in Yemen has created what the UN has described as the world’s worst humanitarian crisis.