Around half of the missiles fired at Israel by Iran were equipped with cluster warheads, the IDF has found.
The military's latest estimates discovered that almost 50 per cent of the munitions use the controversial technology, making them harder to intercept.
Cluster bombs contain dozens of smaller explosives, known as bomblets, which disperse across a wide area before impact.
This allows a single missile to cause indiscriminate damage in multiple locations.
More than 100 countries have prohibited the proliferation or use of cluster munitions since 2008 under the Convention on Cluster Munitions (CCM), but the US, Israel and Iran are not signatories.
Nonetheless, the use of such munitions on civilian targets or in populated areas is widely regarded as a violation of international law and, potentially, a war crime.
The assessment comes after two people were killed by suspected cluster bomb attacks over the weekend.
More than a dozen impact sites were recorded across central Israel on Sunday, suggesting the use of such a missile, police said.
A second strike then saw six more impacts in Yehud, Holon and Bat Yam.
On Monday, authorities confirmed that a Petah Tikva resident had died after suffering shrapnel wounds in the strikes.
The following day, local mayor Rami Greenberg announced that a second person had succumbed to their wounds at the Sheba Medical Centre.
Both men were residents of Peta Tikvah but were working on a construction site in Yehud at the time of the attack.
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