The Saudi-led coalition attacked a funeral in Yemen after receiving "wrong information" that armed Houthi leaders were in the area, an investigative body set up by the coalition said on Saturday.
The Saudi-led campaign in Yemen has come under severe criticism since last Saturday's air strike hit a funeral gathering in the Yemeni capital Sanaa, killing 140 people according to one UN estimate and 82 according to the Houthis.
Mourners killed in the attack included some of Yemen's top political and security officials, outraging Yemeni society and potentially galvanising powerful tribes to join the Houthis in opposing a Saudi-backed exiled government.
"A party affiliated to the Yemeni Presidency of the General Chief of Staff wrongly passed information that there was a gathering of armed Houthi leaders in a known location in Sanaa, and insisted that the location be targeted immediately," the investigators concluded, according to a statement.
The Joint Incidents Assessment Team (JIAT) said in the statement that the coalition's Air Operations Centre in Yemen also failed to obtain approval for the strike from commanders, a violation of protocol.
The JIAT called for a review of the rules of engagement, and for compensation for the families of the victims. It also said "appropriate action" should be taken against those who caused the incident, without elaborating.
Human Rights Watch said that the strike on the funeral was an "apparent war crime."
"While military personnel and civilian officials involved in the war effort were attending the ceremony, the clear presence of several hundred civilians strongly suggests that the attack was unlawfully disproportionate," the New York-based watchdog said on Thursday.
The coalition initially denied responsibility but after condemnation from Western governments, it promised an investigation of the "regrettable and painful" event.
A letter sent to the UN Security Council last weekend "expressed the kingdom's deep regret" over the "attack".
There was huge pressure on the coalition to publish the findings of its investigation into the raid as swiftly as possible.
Meanwhile, an Omani aircraft landed in the rebel-held Yemeni capital on Saturday to evacuate 115 of the most seriously wounded in the attack on the funeral, a spokesman for the Houthis said.
Oman is the only Gulf Arab state that is not part of the Saudi-led coalition fighting the Houthis in Yemen.
The United Nations estimates that 10,000 people have been killed in the war and blames coalition air strikes for 60 per cent of some 3,800 civilian deaths since the attacks began in March 2015.