Human Rights Watch said it investigated the strikes at the schools in three separate locations in the war-battered Gaza Strip, attacks in which at least 45 people were killed.
According to its investigation, based on field research and interviews with witnesses, the New York-based group said no military targets were apparent in the area of the schools and some of the attacks were indiscriminate.
“The Israeli military carried out attacks on or near three well-marked schools where it knew hundreds of people were taking shelter, killing and wounding scores of civilians,” said Fred Abrahams, special adviser at Human Rights Watch. “Israel has offered no convincing explanation for these attacks on schools where people had gone for protection and the resulting carnage.”
Israel argues that the heavy civilian death toll during the 50-day summer war was Hamas’ fault, accusing the Islamic militant group of launching rockets and drawing retaliation from school yards, residential areas, and mosques.
On Wednesday, the Israeli military announced it had launched its own probe into cases involving Palestinian civilian casualties during the war, including the shelling of a UN school.
The announcement was apparently meant to send a signal that Israel can police itself as it faces the spectre of international war crimes probes.
The Gaza war left more than 2,100 Palestinians dead, the majority of them civilians, according to Palestinian and UN officials. Israel says the number of militants killed was much higher and accuses Hamas of using civilians as human shields. On the Israeli side, 66 soldiers and six civilians were killed.
About a quarter of a million Palestinians displaced by the violence were seeking shelter in UN-run schools.
The attacks had elicited widespread condemnation, with UN secretary-general Ban Ki-moon calling one a “moral outrage and a criminal act”.