TEL AVIV, Israel — A new report by an Israeli nonprofit has concluded that sexual violence was systematic, widespread and integral to the Hamas-led attacks of October 7, 2023, and their aftermath, documenting gang rape, sexual torture and forced nudity across multiple attack sites.

The report, titled “Silenced No More,” was published Tuesday by the Civil Commission, an independent group that researches gender-based violence committed by Hamas. It draws on a two-year investigation that encompassed more than 400 testimonies and nearly 2,000 hours of visual analysis, according to the commission’s founder and chair, Cochav Elkayam-Levy, who served as the report’s lead author.

“Our findings demonstrate that it was a deliberate tactic within the broader architecture of the terror inflicted on victims and hostages,” Elkayam-Levy said in a statement accompanying the release.

The commission — composed of researchers, lawyers and trauma experts — identified 13 distinct patterns of sexual violence, including gang rape, sexual torture and forced nudity, and said it cross-referenced its material with independent data sources. Armed groups also recorded acts of abuse and circulated footage through social media, the report found.

The United Nations has previously said it found “reasonable grounds” to believe that Hamas militants committed rape and other sexual violence during the rampage. Karim Khan, the prosecutor for the International Criminal Court, has also stated he had reason to believe that three key Hamas leaders bore responsibility for “rape and other acts of sexual violence as crimes against humanity.”

The report detailed assaults at the Nova Music Festival, where hundreds were killed and others taken hostage. The Associated Press earlier reported witness accounts from the festival, including a man who said he heard a woman screaming for help and shouting, “They’re raping me, they’re raping me.”

Hostages also were subjected to sexual harassment and assault, some lasting for months, the commission said. In one example cited in the report, two young hostages who later returned were forced to perform “sexual acts on one another” — such as removing their clothes while captors touched their private parts. Sexual torture was used to maximize pain and suffering, with survivors enduring burning, mutilation and the forced insertion of objects; victims were sometimes found handcuffed or bound, according to the report’s summary.

Some released hostages have spoken publicly about abuse in captivity. Romi Gonen told Israeli media she was repeatedly sexually assaulted and harassed by three men. Guy Gilboa-Dalal told the New York Times he was sexually abused by one of his captors and threatened with death if he said anything.

Sexual violence has been heavily politicized since the war in Gaza began. Israel has pointed to incidents during the Oct. 7 attacks and to the treatment of hostages to emphasize what it calls Hamas’ savagery and to justify its wartime goal of preventing any repeated threat from Gaza. At the same time, human rights groups and Palestinians rounded up by Israel after the attacks have shared detailed testimonies of sexual violence and torture inside Israeli prisons. In March, Israel dropped charges against five soldiers accused of beating and sodomizing a Palestinian detainee in an alleged assault partially caught on camera; human rights groups said the decision illustrated an unwillingness to investigate abuses.

The AP could not independently verify the commission’s findings. Critics, including some prominent academics, have challenged aspects of Elkayam-Levy’s earlier research, while a number of high-profile figures — including Hillary Rodham Clinton, Rahm Emanuel and Facebook pioneer Sheryl Sandberg — have endorsed her work.

Israel’s government and Hamas did not immediately respond to requests from the AP for comment.