The London-based human rights group said it documented cases involving seven men and one woman, detained over the past two years at the Al-Jadaa camp in northern Iraq.

"Seven of them faced torture and ill-treatment," Amnesty said, describing beatings, electric shocks and suffocation by plastic bags.

Family members observed signs of torture, including broken fingers and dislocated shoulders, the group said in a statement.

"The torture and other ill-treatment suffered by those arrested... is horrifying. It must be stopped and investigated immediately," said Amnesty secretary general Agnes Callamard.

Iraq and the United Nations had agreed to repatriate tens of thousands of Iraqis from Syria's Al-Hol camp, but Callamard called it "unconscionable" that those returning from war and detention face further horrors".

Amnesty said it spoke with detainees, their families and 16 UN staff members during interviews conducted between July and September.

Of the eight cases, seven detainees described torture by Iraqi security forces. Six are now serving lengthy sentences based on forced confessions, it said.

One detainee, identified by the pseudonym Saleem, described his experience.

"They beat me, and... handcuffed my hands behind my back. They hit the soles of my feet with a green water pipe... I was just saying 'no', again and again," he was quoted as saying by Amnesty.

"During the torture, they said they wanted me to confess to things I didn't do. I didn't confess, and so I didn't walk for four days."

Amnesty urged Iraqi authorities to "immediately end the use of torture and other ill-treatment and the enforced disappearance of those arrested" at Al-Jadaa.

The non-governmental organisation said it had requested but was denied access to interview detainees in July due to "security concerns".

On October 2, Amnesty said it wrote to Iraq's prime minister with its findings but has not received a response.

Iraq is one of the few countries to regularly repatriate its nationals from Al-Hol, a policy welcomed by the United Nations and the United States.

Since 2021, Iraqi forces have arrested about 80 people in the camp on charges of affiliation with the Islamic State group, Amnesty said.

While some arrests may be "legitimate", Amnesty noted accusations have occasionally stemmed from personal quarrels or a relative with ties to IS.

As of September, Al-Jadaa held 2,223 people, including 1,318 children, 627 women and 278 men, the rights group said.