Iraqi special operations forces arresting a person suspected of belonging to ISIS in western Mosul, Iraq, on February 26. REUTERS/Alaa Al-Marjani

As US-backed forces stand on the brink of retaking Mosul, Iraq, reports continue to emerge that they are summarily executing captured fighters from the Islamic State, the terrorist group also known as ISIS, ISIL, or Daesh.

ISIS fighters are sometimes executed at the front lines, while others are executed after being interrogated, a Mosul-based commander told Integrated Regional Information Networks, a nonprofit media site that focuses on conflict zones.

Extrajudicial killings of ISIS fighters have been emerging pretty much since the fight for Mosul began about seven months ago.

In late 2016, a video appeared showing Iraqi soldiers dragging a suspected ISIS fighter along the ground, then crushing him with a tank before shooting him. In January, another video emerged showing Iraqi troops dragging and beating three ISIS fighters as they begged for their lives. The three were then shot dead and trampled.

Many more such incidents have been reported and alleged.

The barbarity of ISIS fighters, who have repeatedly executed Mosul residents accused of collaborating with Iraq's army, seems to have done them no favors. They are viewed with disgust and hatred by the US-backed forces.

Still, "killing captured combatants or civilians is a war crime, as is the mutilation of corpses," Belkis Wille, Human Rights Watch's senior researcher in Iraq, told IRIN.

But investigating abuse is not a priority in Iraq at the moment. Some executions are apparently being overseen – or at least condoned – by senior military personnel.

The Iraqi Army is also accused of mutilating and taking selfies with dead ISIS fighters. A Human Rights Watch report in March said 1,269 ISIS prisoners were held without charge in "horrendous" and "degrading" conditions in three jails near Mosul.

Read the full IRIN report here >