Iraqi military commanders should prevent militias with records of serious abuse from taking part in a planned offensive on the Islamic State of Iraq and the Levant-held city of Mosul, a New-York based rights group has said.
The battle for Mosul, ISIL's de facto capital in Iraq and the largest city anywhere in its self-proclaimed caliphate, is expected later this year but plans have not been finalised, officials and diplomats in Baghdad have said.
Army, police and special forces are expected to participate, with air support from a US-led coalition.
The role of Kurdish Peshmerga forces and Shia militias from the Popular Mobilisation Forces (PMF) is unresolved and remains a point of contention. They are likely to join in the larger battle but may be restricted to the city's outskirts, the officials said.
"Iraqi commanders shouldn't risk exposing Mosul civilians to serious harm from militias with a record of recent abuse," said Joe Stork, deputy Middle East director at Human Rights Watch.
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Shia militia and Peshmerga fighters have been key forces in Iraq's campaign to retake the third of the country seized by ISIL, also known as ISIS, in 2014 after army and police units collapsed, but they have also been accused of abuses against civilians, allegations they deny or dismiss as isolated cases.
Their participation in the battle for Mosul, a predominately Sunni Arab city which also has diverse ethnic and sectarian communities, risks confrontation with the local population.
Militia leaders say the security forces have not been rebuilt enough to retake the city by themselves in a battle that could see fierce street fighting.
Mosul officials, displaced to other parts of the country, say alleged abuses in the city of Fallujah in May, alongside those in previous battles, vindicate their calls to keep the militias out of the northern city.
Several militias faced allegations in Fallujah from the provincial governor, which they denied, that they executed 49 Sunni men and detained more than 600 others.
The authorities opened an investigation and made several arrests at the time.