The rights group said five air strikes hitting four family homes and a grocery store were carried out either deliberately or recklessly, causing indiscriminate loss of civilian lives in violation of the laws of war.

"The Saudi-led coalition's repeated promises to conduct its air strikes lawfully are not sparing Yemeni children from unlawful attacks," said Sarah Leah Whitson, Middle East director at Human Rights Watch, in a statement.

"This underscores the need for the United Nations to immediately return the coalition to its annual "list of shame" for violations against children in armed conflict," she said.

On August 4, coalition aircraft struck a home in Saada, killing nine members of a family, including six children, ages 3 through 12.

On July 3, an air strike killed eight members of the same family in Taiz province, including the wife and 8-year-old daughter, the organisation said.

HRW said it interviewed nine family members and witnesses to five air strikes that occurred between June 9 and August 4, and did not detect any potential military targets in the vicinity.

The war has killed more than 10,000 people, displaced more than three million and ruined much of the impoverished country's infrastructure.

HRW called on United Nations Security Council to launch an international investigation into the abuses at its September session.

On Monday, the U.N. said it has verified 5,144 civilian deaths in the war in Yemen, mainly from air strikes by a Saudi-led coalition, and an international investigation is urgently needed.