Dozens of people, many of them children, were killed in Saudi-led coalition air strikes on August 9 in Yemen's Saada province, the International Committee of the Red Cross (ICRC) and local medical sources said.
The ICRC said one one strike targeted a bus driving children in Dahyan market, in northern Saada. Hospitals in the area received dozens of dead and wounded, the ICRC said.
The Western-backed coalition, which is fighting Iranian-backed Huthi rebels in Yemen, said in a statement that it targeted missile launchers used to attack the southern Saudi industrial city of Jizan, and accused the Huthis of using children as human shields.
"Today's attack in Saada was a legitimate military operation ... and was carried out in accordance with international humanitarian law," the Arabic-language statement said.
It was unclear how many children were killed and how many air strikes were carried out in the area, in northern Yemen, near the border with Saudi Arabia.
The Huthi rebels' health ministry said at least 43 people were killed, and 61 were wounded. The ICRC said most of the victims were under 10 years old.
"Scores killed, even more injured, most under the age of 10," Johannes Bruwer, head of delegation for the ICRC in Yemen, said in a twitter post.
Saudi Arabia and Sunni Muslim allies have been fighting in Yemen for more than three years against the Huthis, who control much of north Yemen including the capital Sanaa and drove the government into exile in 2014.
Almost 10,000 people -- a vast majority of them civilians - have been killed since the Huthis took control of the north in 2014, when they forced President Abd-Rabbu Mansur Hadi into exile in neighboring Saudi Arabia.