In recent years Iraqi courts have ordered hundreds of executions in "terror" cases, proceedings that rights groups say often lack due process or in which confessions suspected to have been extracted through torture are admissible.

In a joint statement Thursday, five rights groups and two activists called on the Iraqi government to "immediately halt the secret executions and torture... that prisoners are being subjected to".

They urged "investigations into unlawful executions... and suspicious deaths in custody", as well as ensuring that prisoners in the country's Nasiriyah prison are treated "with respect for their dignity".

Several rights groups have previously criticised the poor conditions in the Nasiriyah facility, widely dubbed Al-Hut prison, meaning "the whale" in Arabic, because it is believed those who enter do not come out alive.

Human Rights Watch in November accused Iraq's authorities of widening the "scale and pace of unlawful executions in 2024", calling on them to "urgently halt all pending executions and declare a moratorium".

It said at the time that about 8,000 people were believed to be on death row in Iraq.

The statement on Thursday said prisoners were underfed and often given expired food, as well as "water unfit for drinking".

The signatories called for "providing healthcare to the inmates", citing the spread of tuberculosis among prisoners.

French lawyer Olfa Ouled meanwhile told AFP "all my clients of Iraqi nationality were sentenced to death, on the basis of confessions extracted under torture and following summary trials".

She insisted they were innocent, urging the authorities to release them "without delay".

"This would do justice not only to the victims of these arbitrary sentences and their families but also to the families of the victims who have lost their loved ones without the real culprits being brought to justice," she said.

Some 50 people were executed in September on various charges including "terrorism", according to AFAD, an independent group monitoring rights violations in Iraq and one of the signatories of Thursday's statement.

In June, AFAD condemned what it described as a surge in "secret executions", pointing to 63 such cases that were not publicly announced in previous weeks.