The Saudi-led coalition has been using US-supplied cluster bombs in its air campaign against Yemeni rebels, Human Rights Watch said on Sunday, warning of the long-term dangers to civilians.
The widely banned munitions contain dozens of submunitions, which sometimes do not explode, becoming de facto landmines that can kill or maim long after they were dropped.
HRW said it had gathered photographs, video and other evidence indicating that cluster munitions had been used in coalition air strikes against the Huthi rebel stronghold of Saada province in Yemen's northern mountains.
It said that analysis of satellite imagery suggested that the weapons had landed on a cultivated plateau, within 600 metres (yards) of populated areas.
Cluster munitions are prohibited by a 2008 treaty adopted by 116 countries, but not by Saudi Arabia and its coalition partners or the United States.
"Saudi-led cluster munition air strikes have been hitting areas near villages, putting local people in danger," said HRW arms director Steve Goose.
"Saudi Arabia and other coalition members -- and the supplier, the US -- are flouting the global standard that rejects cluster munitions because of their long-term threat to civilians."
HRW said that the munitions used in Yemen appeared to be the CBU-105 Sensor Fuzed Weapons manufactured by the Textron Systems Corporation and supplied to both Saudi Arabia and the United Arab Emirates by the United States in recent years.
The weapon is banned by the Convention on Cluster Munitions but Washington permits its use and export because it boasts an unexploded ordnance rate of less than one percent.
HRW called for that loophole to be closed and for deliveries of the weapons to cease.