Amnesty International said on Thursday that Iran fired cluster munitions at Israel during last month’s war between the two countries, in attacks that endangered civilians.

The report backs up an assessment by the Home Front Command, made during the war, that Iran fired at least one cluster bomb warhead at central Israel. Iran was suspected of firing a cluster bomb at Beersheba in southern Israel as well.

“Last month, the Iranian forces fired ballistic missiles whose warheads contained submunitions into populated residential areas of Israel,” the human rights group said, citing new research. It said international law “prohibits the use of inherently indiscriminate weapons, and launching indiscriminate attacks that kill or injure civilians constitutes a war crime.”

Cluster munitions explode in mid-air and scatter bomblets. Some of them do not explode on impact and can cause casualties over time, particularly among children.

“By using such weapons in or near populated residential areas, Iranian forces endangered civilian lives,” said Erika Guevara Rosas, senior director at Amnesty International.”Iranian forces’ deliberate use of such inherently indiscriminate weapons is a blatant violation of international humanitarian law.”

Neither Iran nor Israel is among more than a hundred countries that are party to the 2008 Convention on Cluster Munitions, which prohibits the use, transfer, production and storage of cluster bombs. Israel used cluster munitions in its 2006 war against Hezbollah in Lebanon and later said it would limit its deployment of them.

The 12-day Israel-Iran war began in mid-June when Israel struck Tehran’s top military leaders, nuclear scientists, uranium enrichment sites, and ballistic missile program, an attack it said was necessary to prevent the Islamic Republic from realizing its avowed plan to destroy the Jewish state.

Iran has consistently denied seeking to acquire nuclear weapons. But it enriched uranium to levels that have no peaceful application, obstructed international inspectors from checking its nuclear facilities, and expanded its ballistic missile capabilities. Israel said it had recently taken steps toward weaponization.

Iran retaliated to Israel’s strikes by launching over 500 ballistic missiles and around 1,100 drones at Israel. The attacks killed 29 people and wounded over 3,000 in Israel, according to health officials and hospitals.

In all, there were 36 missile impacts and one drone strike in populated areas, causing damage to 2,305 homes in 240 buildings, along with two universities and a hospital, and leaving over 13,000 Israelis displaced. Iran said its death toll in the war topped 1,000.

Amnesty said it analyzed photos and videos showing cluster munitions that, according to media reports, struck a home in Azor, near Tel Aviv, on June 19.

On top of that, the southern city of Beersheba on June 20 and the central city of Rishon LeZion on June 22 were also “struck with ordnance that left multiple impact craters consistent with the submunitions seen in Gush Dan,” the Tel Aviv district, Amnesty said.

Amnesty has been harshly critical of Israel in the past. Thursday’s report came two days after the group called for a war crimes investigation into Israel’s deadly air attack on Tehran’s notorious Evin prison during the war. The strike, confirmed by Israel, killed 79 people, according to a provisional tally by Iranian authorities. The toll has not been verified.

Amnesty International called the Israeli attack “deliberate” and “a serious violation of international humanitarian law” that killed civilians. The airstrikes should be “criminally investigated as war crimes,” it said.

IDF Spokesman Brig. Gen. Effie Defrin previously stated that “within the prison compound, intelligence activity was carried out against Israel, including counter-espionage,” and that the strike was carried out “in a pinpoint manner, to avoid harm to those uninvolved.”

Amnesty has also accused Israel of committing genocide in Gaza, a charge Israel adamantly denies. Amnesty Israel, the group’s local branch, rejected that report and was later reportedly suspended.