The Saudi-led coalition backing the Yemeni government acknowledged Thursday there may have been "collateral damage" from August 23 strikes that the UN says killed 26 children south of the port of Hodeida.
The coalition has drawn heavy UN criticism for the high civilian death toll from its more than three-year-old bombing campaign in Yemen.
Coalition commanders have admitted a small number of mistakes but have accused the rebels of routinely using civilians as human shields.
Despite repeated calls from the United Nations and human rights group, there has been no public disciplinary action or changes to the coalition's rules of engagement.
In the August 23 strikes, coalition warplanes killed 26 children and four women in Al-Durayhimi, UN humanitarian operations chief Mark Lowcock said the following day.
The coalition said on Thursday that its joint forces command had now completed an after-action review of the strikes.
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"According to the results of the comprehensive review... there might have been collateral damage and civilian casualties," coalition spokesman Colonel Turki al-Maliki said in a statement carried by the official Saudi Press Agency.
"All documents relating to this incident have been handed over to the Joint Incidents Assessment Team pending assessment and announcement of results," he added, without elaborating on what they might be.
Human rights groups have charged that the coalition's internal investigations are "laughable" and fail to hold to account commanders responsible for possible war crimes.
A spate of coalition strikes that killed civilians, many of them children, last month has triggered pressure for action, even from the Gulf Arab states' main Western arms suppliers.
The coalition expressed regret on Saturday after its inquiry into an August 9 strike that killed 51 people, including 40 children, in the rebel-held north found that "mistakes" had been made.
The United States said it was "an important first step toward full transparency and accountability".
Spain's new Socialist government said it had cancelled a deal signed by the previous conservative administration in 2015 to sell 400 laser-guided bombs to Saudi Arabia.
UN investigators said on Tuesday that all sides in Yemen's conflict may have committed war crimes, highlighting deadly air strikes, rampant sexual violence and the recruitment of young children as soldiers.
The rebels, who still control the capital Sanaa and much of the north as well as the Red Sea port city of Hodeida, accuse the coalition of knowingly targeting children.