Israel used widely banned cluster munitions in its recent 13-month war in Lebanon, photos of munition remnants in south Lebanon seen by the Guardian suggest.

The images, which have been examined by six different arms experts, appear to show the remnants of two different types of Israeli cluster munitions found in three different locations: south of the Litani River in the forested valleys of Wadi Zibqin, Wadi Barghouz and Wadi Deir Siryan.

The evidence is the first indication that Israel has used cluster munitions in nearly two decades since it employed them in the 2006 Lebanon war. It would also be the first time that Israel was known to have used the two new types of cluster munitions found – the 155mm M999 Barak Eitan and 227mm Ra’am Eitan guided missiles.

Cluster munitions are container bombs which release many smaller submunitions, small “bomblets”, over a wide area the size of several football fields. The use of cluster munitions is widely banned as up to 40% of submunitions do not explode upon impact, posing a danger to civilians who might later stumble upon them and be killed when they explode.

To date, 124 states have joined the convention on cluster munitions, which forbids their use, production and transfer. Israel is not a party to the convention and is not bound by it.

“We believe the use of cluster munitions is always in conflict with a military’s duty to respect international humanitarian law because of their indiscriminate nature at time of use and afterwards,” said Tamar Gabelnick, the director of the Cluster Munition Coalition. “Their wide area impact means they cannot distinguish between military and civilian targets and the cluster munition remnants kill and maim civilians for decades after use.”

The Israeli military neither confirmed nor denied its use of cluster munitions but said it “uses only lawful weapons, in accordance with international law and while mitigating harm to civilians”.

Israel’s war with Hezbollah which started in October 2023 and killed almost 4,000 people in Lebanon and about 120 people in Israel. Much of Lebanon’s south remains in ruins and Israel still carries out near-daily airstrikes in the country, despite a ceasefire signed last year.

Lebanon in particular has a painful history with cluster munitions. Israel blanketed Lebanon with 4m cluster bombs in the final days of the 2006 war, with an estimated 1m failing to explode. The presence of unexploded cluster bombs continues to make life in south Lebanon dangerous, with more than 400 people killed by unexploded bomblets since 2006.

The huge number of unexploded cluster bombs in Lebanon was a main driving factor for the drafting of the cluster convention in 2008.