Three women and six children from the same family were killed in an air strike by the Saudi-led coalition on their home in northern Yemen on Friday.
A top United Nations official in Yemen said reported air strikes in which at least 12 civilians were killed, including children, were an example of the "disregard" for civilians' safety shown by all the combatants in Yemen's civil war.
The civilians were killed and 10 others wounded in Sa'ada province after attacks on a house and a private vehicle, the UN's Humanitarian Coordinator in Yemen Jamie McGoldrick said, citing reports from fellow aid groups.
Three women and six children from the same family were killed in an air strike by the Saudi-led coalition on their home in the area, according to a local health official.
A spokesman for the Saudi-led coalition did not respond to a request for a comment.
Yemen has been torn apart by a civil war in which the exiled government of President Abd-Rabbu Mansour Hadi, backed by the Saudi-led coalition, is trying to push back gains made by the Iran-aligned Houthi rebels who controls most of the north, including the capital Sanaa.
The new incidents were an example of the "brutality" of the conflict, McGoldrick said in the statement in which he expressed deep concern.
"All parties to the conflict continue to show a disregard for the protection of civilians and the principle of distinction between civilians and combatants in the conduct of hostilities."
Saada, a stronghold of the Houthi rebels, has been repeatedly hit by air strikes since the Saudi-led coalition joined the civil war in March 2015. They see the war as an attempt by Iran to expand its influence in Yemen.