Israeli security forces' shackling of Palestinian prisoners is frequently cruel and humiliating and in a number of instances constitutes "torture," a rights group said Wednesday.

The army and the internal security forces "shackle detainees in painful and humiliating manners that, in a number of instances, rise to the level of torture," the Public Committee Against Torture in Israel (PCATI) said.

The group published its findings in a report based on 547 cases of arrests and dozens of interrogations conducted over the past year.

"Painful shackling is done for invalid and irrelevant reasons, which include causing pain and suffering, punishment, intimidation and illegally eliciting information and confessions," the group said.

It added that the victims were mostly Palestinians detained for "security" reasons but that the practices had seeped into the facilities where other categories of detainees are held.

The group added that its findings were supported by the testimony of soldiers to Breaking the Silence, another Israeli organisation.

The group said detainees are often shackled in painful positions for hours or days at a time, even when they are being held in highly secure facilities and are not being interrogated.

"Painful shackling is designed to break the interogee's spirit and to illegally extract a confession or information from him, in violation of Israel's obligations under the UN Convention Against Torture."

The military denied it inflicted pain on Palestinian detainees, saying it "respects international and Israeli law regarding the treatment of suspected terrorists who threaten the security of Israel."

The Shin Beth internal security service issued a similar statement in response to the report, saying it only used handcuffs to protect interrogators and prevent prisoners from escaping.