The UN human rights office has reported that Palestinian detainees taken by Israeli authorities since the October 7 attacks have faced waterboarding, sleep deprivation, electric shocks, the release of dogs, and other forms of torture and mistreatment.

The report on detention says Israel’s prison service held more than 9,400 “security detainees” as of the end of June, and some have been held in secret without access to lawyers or respect for their legal rights.

A summary of the report, based on interviews with former detainees and other sources, decries a “staggering” number of detainees – including men, women, children, journalists and human rights defenders – and said such practices raise concerns about arbitrary detention.

UN human rights chief Volker Turk said: “The testimonies gathered by my office and other entities indicate a range of appalling acts, such as waterboarding and the release of dogs on detainees, amongst other acts, in flagrant violation of international human rights law and international humanitarian law.”

Findings in the report, one of the most extensive of its kind, could be used by International Criminal Court prosecutors who are looking into crimes committed in connection with the October 7 attacks and their aftermath, including Israel’s blistering military campaign that is ongoing in Gaza.

Authors of the report said its content was shared with the Israeli government.

The report says detainees were taken in Gaza, Israel and the West Bank, and says Israel has not provided information regarding the fate or whereabouts of many, adding that the International Committee of the Red Cross has been denied access to facilities where they are held.

The report’s summary said: “Detainees said they were held in cage-like facilities, stripped naked for prolonged periods, wearing only diapers.

“Their testimonies told of prolonged blindfolding, deprivation of food, sleep and water, and being subjected to electric shocks and being burnt with cigarettes.

“Some detainees said dogs were released on them, and others said they were subjected to waterboarding, or that their hands were tied and they were suspended from the ceiling,” it added.

“Some women and men also spoke of sexual and gender-based violence.”

The report also says the Palestinian Authority, which administers parts of the Israeli-occupied West Bank, had also “continued to carry out arbitrary detention and torture or other ill-treatment in the West Bank, reportedly principally to suppress criticism and political opposition”.

On Tuesday, an Israeli military court began an initial hearing for nine soldiers detained over what a defence lawyer said were allegations of sexual abuse of a Palestinian at Sde Teiman – a shadowy facility where Israel has held prisoners from Gaza during the war.

The soldiers’ detention triggered angry protests by supporters demanding their release.

On Wednesday, the military court extended the detention of eight Israeli suspects until Sunday.

The war in Gaza erupted after Hamas’ surprise attack on southern Israel on October 7, killing some 1,200 people that day and taking 250 others hostage.

Israel’s retaliatory operation has obliterated entire neighbourhoods in Gaza and forced some 80% of the population to flee their homes.

Gaza’s health ministry says more than 39,000 Palestinians have been killed, without distinguishing between civilians and combatants in its count.