The report bears witness to 55 former prisoners describing "inhumane conditions" and that the prisons were used as "actual torture camps".
The report refers to the time after Hamas' terrorist attack on Israel on October 7, which triggered the ongoing war in Gaza.
The former prisoners describe frequent acts of severe, arbitrary violence, sexual assaults, humiliation, intentional starvation, and sleep deprivation, according to the report.
Israel's prison authority rejects the allegations, considering them baseless. According to the authority, all prisoners are held "legally and their fundamental rights are fully ensured".
Israel's military also states that all types of abuse against prisoners are illegal and contrary to military guidelines.
B'Tselem's report is published a week after the UN human rights organization also accused Israel of subjecting prisoners to torture-like methods.
According to the human rights group, the Israeli prisons and detention centers have almost doubled to over 9,600 since before the war.
