Amnesty International has welcomed yesterday's release of four anti-government protesters reported missing since their arrest in Baghdad on Monday and called on the authorities to free others still in detention.
The four were among at least 10 people detained while returning home from a protest against unemployment, government corruption and poor social services.
"While the release of these four detainees is a welcome step, the authorities must reveal where the remaining detainees are held and release them if they have been detained solely for exercising their legitimate right to protest," said Malcolm Smart, Amnesty International's director for the Middle East and North Africa.
"The Iraqi authorities must also ensure that those still in detention are not tortured or ill-treated and order an immediate independent investigation into all previous allegations of torture, bringing those responsible to justice."
Those detained on Monday include Ala' Sayhoud, Ma'an Thamer, 'Ali Abdel Zahra' and Muhammad Kadhim Finjan.
They were arrested by Iraqi security forces in Baghdad's al-Batawin area after they participated in a demonstration in the city's Tahrir Square.
As calls for reform persist in the country, Amnesty International has also called on the Iraqi authorities to respect the right of assembly and freedom of expression.