The Saudi-led Arab military coalition says it will investigate an air strike that killed dozens of children in Yemen, an apparent shift of stance on an attack Riyadh has portrayed as a legitimate action against its Houthi foes.
At least 40 children were killed in Thursday's strike on a bus in northern Yemen, the armed Houthi group which controls Yemen's capital said.
That raised the toll of children killed in the raid from 29.
The strike by the Western-backed alliance of Arab countries outraged human rights groups and was strongly condemned by UN officials.
Henrietta Fore, executive director of the UN Children's Fund UNICEF, said the "horrific" attack marked "a low point in (Yemen's) brutal war".
People in Saada started to dig graves in preparation for funerals to be held on Saturday.
"God may give us patience," said Hussein Hussein Tayeb, who lost three sons on the bus, on a trip with other pupils to visit a mosque and tombs.
UN chief Antonio Guterres called for an independent investigation of the raid which hit the bus as it drove through a market in Dahyan, in the Houthis' home province of Saada.
The UN Security Council urged a "credible and transparent" investigation.
The Arab states carried out new air strikes on Friday, killing a girl and injuring several other people whose home was targeted in Marib province, east of the capital Sanaa, the Houthis' al-Masirah TV said.
Announcing the probe into the bus attack, the Saudi Press Agency quoted an alliance official as saying: "The coalition is firmly committed to investigating all claims regarding mistakes or violations of international law, to sanction those who caused these incidents and to provide assistance to the victims."
The Saudi-led Arab alliance has been fighting for three years to drive out the Houthis, Iran-aligned fighters who pushed a Saudi-backed government out of the capital in 2014.
A Yemeni stands near a destroyed bus at the site of a Saudi-led airstrike. Source: AAP
The Arab states initially said the air strikes on the bus were "legitimate military action" against missile launchers.
Houthi-run al-Masirah TV cited the group's health minister Taha Mutawakil as saying that the estimated number of casualties stood at 51 killed including 40 children, and at least 79 people wounded, of whom 56 were children.
The International Committee of the Red Cross reported the same toll on Friday, citing authorities in Saada.
It had said on its Twitter account on Thursday that its medical team at the ICRC-supported hospital in Saada had received the bodies of 29 children, all under 15 years old. The hospital also received 48 wounded people, among them 30 children.
