“This year’s use of cluster munitions shows that while these weapons have been banned by most countries of the world, some actors still flout international opinion and standards,” Mary Wareham, the advocacy director of Human Rights Watch’s arms division and an editor of the report, said in a statement issued by the coalition in advance of the report’s release.

The group’s statement said, “Already, casualties in Syria are higher than those attributed to the 2006 Israel-Lebanon conflict that triggered global outrage and contributed to the establishment of the ban convention.”

Israel’s military was widely criticized at home and abroad for its heavy cluster-bomb use in Lebanon, dropping around 1,800 of them, containing more than 1.2 million bomblets, particularly in the final days of the 34-day conflict with Hezbollah. The Israeli newspaper Haaretz quoted a commander of the Israel Defense Forces as saying, “What we did was insane and monstrous, we covered entire towns in cluster bombs.”

Jan Egeland, a Norwegian statesman and diplomat who at the time of the Lebanon conflict was the top humanitarian aid official at the United Nations, described Israel’s use of the weapons as “completely immoral.” Mr. Egeland’s criticism was widely credited with helping to galvanize the efforts to achieve a treaty two years later known as the Convention on Cluster Munitions.

Cluster bombs contain hundreds of small explosive munitions, or bomblets, usually dropped from aircraft or fired by artillery. They are engineered to explode in midair and scatter the bomblets over a vast area, not distinguishing between military and civilian targets. Many of the bomblets fail to explode and can lie dormant for decades. In Vietnam and Laos, where the United States dropped many cluster bombs during the Vietnam War era, unexploded bomblets still pose a threat.