Amnesty International has said it had identified a pattern of attacks by Iraqi forces and the US-led military coalition backing them that violated international humanitarian law and may amount to war crimes.

It also said that fighters from the Islamic State of Iraq and the Levant (ISIL, also known as ISIS) group flagrantly violated that same law by deliberately putting civilians in harm's way to shield its fighters and impede the advance of Iraqi and coalition forces.

In a report published a day after Iraqi forces declared victory in Mosul, the human rights watchdog called for a thorough investigation into whether war crimes were committed in the battle for the city.

Iraqi Prime Minister Haider al-Abadi formally declared victory in Mosul on Monday, three years after the ISIL group seized the city.

With air support from the US-led coalition, Iraqi forces launched the battle for Mosul in October, retaking the eastern part of the city in January and starting the operation for its western part the next month.

'Disproportionate attacks'

Amnesty said Iraqi forces and the coalition carried out a series of unlawful attacks in west Mosul, relying heavily on Improvised Rocket Assisted Munitions (IRAMs), explosive weapons with crude targeting capabilities that wreaked havoc in densely populated areas.

"Even in attacks that seem to have struck their intended military target, the use of unsuitable weapons or failure to take other necessary precautions resulted in needless loss of civilian lives and in some cases appears to have constituted disproportionate attacks," the report said.

Amnesty also slammed ISIL for a host of crimes that have been documented previously.

According to the report, ISIL fighters rounded up residents in contested villages and neighbourhoods and forced them to move into conflict zones in west Mosul for use as human shields. As clashes neared, they trapped the civilians inside houses without access to food or medical care, it said.

READ MORE: Humanitarian situation dire in 'liberated' Mosul

Amnesty acknowledged the challenges of protecting civilians given ISIL tactics but blamed Iraqi authorities and the US-led coalition for failing to take feasible precautions to protect civilians from air attacks. It said leaflet drops warning of attacks had been virtually useless because ISIL heavily restricted civilian movement.

Neither the Iraqi defence ministry nor coalition officials were immediately available to comment on the Amnesty report.

Chatham House fellow Renad Mansour told Al Jazeera that while "war crimes have certainly" been committed by all sides in Mosul, the extent remains to be unknown.

"The question is whether the Iraqi government will be able to address the human right violations," he said from London.

'Hell on earth'

Also on Tuesday, UN human rights chief Zeid Ra'ad Al Hussein called for accountability and dialogue to heal the trauma of Mosul in the aftermath of the nearly nine-month long battle.

"The women, children and men of Mosul have lived through hell on earth, enduring a level of depravity and cruelty that is almost beyond words," Al Hussein said.

The UN high commissioner demanded that the offenders are brought to justice and all violations thoroughly probed. He also urged Iraq to join the International Criminal Court (ICC).

READ MORE: UN: 20,000 civilians trapped in ISIL-held Mosul areas

"The root causes of violence and conflict in Iraq need to be addressed in terms of human rights violations suffered by all communities in the country over several decades. Only then can secure foundations be laid for the lasting peace that the Iraqi people deserve," Zeid said.

He added that "ISIL forced tens of thousands of people from their homes in and around the city and used them as human shields, a war crime under international humanitarian law and a violation of the most basic standards of human dignity and morality".

The UN said on Monday there was no end in sight to Iraq's humanitarian crisis.

Of the more than 897,000 people displaced from Mosul, the UN said thousands of residents will probably not be able to return to the city because of "extensive damage caused during the conflict".



