The center said in a statement that its legal team provided consultations to hundreds of detainees participating in the flotilla, amid testimonies of physical and psychological abuse, including electric shocks, rubber bullet injuries, and broken ribs, in addition to "insults and harassment of a sexual nature."
He added that a number of detainees were taken to the hospital before being returned to detention, while lawyers documented cases of people suffering from breathing difficulties and suspected rib fractures.
The center noted that the detainees were subjected to violence during the takeover of the boats and during their transfer to the port, including being forced into painful and humiliating physical positions, and some being forced to kneel for long periods inside the military boats.
Testimonies, according to the center, also spoke of the headscarf being forcibly removed from a number of participants, in addition to activists being subjected to insults, incitement and humiliation.
Adalah explained that the Israeli authorities imposed strict restrictions that prevented the legal team from meeting with all the detainees, adding that most of them are currently being transferred to Ketziot prison in the Negev desert, in preparation for presenting them before a judicial body to consider their detention and deportation.
The center reiterated its demand for the "immediate and unconditional" release of all participants in the flotilla, considering their detention "illegal".
Earlier on Wednesday, a video posted by Israeli National Security Minister Itamar Ben-Gvir sparked international outrage after it showed the mistreatment of detained flotilla activists.
As a result, seven European countries, including Spain, France and Italy, summoned their Israeli ambassadors to protest the incident, while several countries, including Türkiye, Britain, Germany, Ireland and Switzerland, issued condemnations.
On Tuesday evening, the Israeli Foreign Ministry announced that all activists of the "Steadfastness Flotilla" had been arrested and transferred to Israeli Navy ships.
According to the flotilla organizers, the Israeli occupation army intervened against all of its approximately 50 boats, carrying 428 activists from 44 countries, including 78 Turkish citizens.
The move was met with widespread condemnation from human rights organizations, including Amnesty International, which described it as a "shameful and inhumane act".
Israel has previously seized aid boats in international waters bound for Gaza on several occasions, some belonging to the Freedom Flotilla campaigns, and detained the activists before later deporting them.
The approximately 2.4 million Palestinians in the Gaza Strip are living in catastrophic humanitarian conditions, exacerbated by the Israeli war that left tens of thousands dead and wounded, most of them women and children.
