TEL AVIV, Israel — Sexual violence was systematic, widespread and integral to the Hamas-led Oct. 7 attacks and their aftermath, a new report by an Israeli nonprofit has found.

The report, titled “Silenced No More,” was published Tuesday by the Civil Commission, an independent group that documents and researches gender-based violence by Hamas after its 2023 attack on Israel that sparked the war in Gaza.

The report details a two-year investigation that drew on more than 400 testimonies and nearly 2,000 hours of visual analysis documenting 13 patterns of violence, including gang rape, sexual torture and forced nudity.

“Our findings demonstrate that it was a deliberate tactic within the broader architecture of the terror inflicted on victims and hostages,” said Cochav Elkayam-Levy, founder and chair of the commission and lead author of the report.

Sexual violence has been heavily politicized since the war in Gaza began, with each side trying to discredit the other’s accusations.

Israel has pointed to incidents during the Oct. 7 attacks and to treatment of hostages to highlight what it says is Hamas’ savagery and to justify its wartime goal of preventing any repeated threat from Gaza. The Israeli government has accused the international community of ignoring or playing down evidence of sexual violence, alleging anti-Israel bias.

The report’s findings could not be independently verified by The Associated Press, and critics have challenged some of Elkayam-Levy’s previous research. A number of prominent figures, including Hillary Rodham Clinton, Rahm Emanuel and Facebook pioneer Sheryl Sandberg, have endorsed her work.

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

Human rights groups and Palestinians rounded up by Israel after the attacks have also shared detailed testimonies of sexual violence and torture in Israeli prisons.

In March, Israel dropped charges against five soldiers who had been accused of beating and sodomizing a Palestinian detainee in an alleged assault partially caught on camera. Hard-line politicians, who had angrily protested the charges, hailed the decision to dismiss the charges, while human rights groups said it illustrated Israel’s unwillingness to investigate abuses.

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

The commission — composed of a team of researchers, lawyers and trauma experts — collected digital materials, conducted interviews and filmed testimonies. It also cross-referenced information using independent data sources, it said.

The report said Hamas and its collaborators primarily targeted women and hostages but that children also were subjected to violence and abuse.

In one example, it said two returning young hostages were forced to perform “sexual acts on one another,” such as taking off their clothes while their captors touched their private parts.

It said sexual torture was used to maximize pain and suffering, with survivors enduring burning, mutilation and forced insertion of objects. Victims were sometimes found handcuffed or bound. Armed groups also recorded acts of abuse and killing and circulated footage through social media, the report said.

The report documented assaults at multiple sites, including the Nova Music festival, where hundreds were killed and others taken hostage. The AP previously found evidence that sexual assault was part of Hamas’ atrocities-filled rampage on Oct. 7, including a witness account by a man at the festival 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 for months at a time, according to the report.

Some released hostages have spoken out about being sexually assaulted in captivity. In an interview with Israeli media, Romi Gonen said she was repeatedly sexually assaulted and harassed by three men.

Another hostage, 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.