A sickening video has emerged of Iraqi forces torturing and executing three ISIS militants.

The harrowing footage, which has deeply concerned the United Nations, shows uniformed men parading three suspected terrorists through the streets of Mosul, Iraq.

One soldier holding a stick drags his victim across the ground by his foot as he desperately pleads for mercy while being kicked by another soldier.

A sickening video has emerged of Iraqi forces torturing and executing three ISIS militants

Another victim is kicked on the ground by a group of men as gunshots can be heard in the background.

The original video then goes on to show the man being shot at point black range by a soldier who continues to fire and stamp on his head after he is dead.

The two other ISIS fighters are also shot in a barrage of automatic fire.

The United Nations Assistance Mission for Iraq (UNAMI) on Saturday urged the Iraqi government to launch investigations into the video report.

The UN said: 'UNAMI calls on the government of Iraq to investigate a video report circulating on social media sites which purportedly shows the brutal mistreatment and murder of at least three captured ISIL members.'

The video emerged shortly before Iraq's prime minister declared eastern Mosul 'fully liberated' from Islamic State.

Iraqi forces drove Islamic State militants from one of their last bastions in the eastern half of the city, while aid groups expressed concern for the estimated 750,000 people still in the militant-held west.

The ISIS fighters pleaded for mercy from the Iraqi troops but none was granted

In his weekly news conference on Tuesday, Haider al-Abadi hailed the 'unmatched heroism of all security forces factions' and public support for the operation.

'Daesh has quickly collapsed and no one expected such collapse,' al-Abadi said, using the Arabia acronym of IS. 'The heroism of our security forces was behind Daesh's defeat.'

Mosul, Iraq's second-largest city and the ISIS's last urban stronghold in the country, fell into the hands of the extremists in the summer of 2014, when the group captured large swaths of northern and western Iraq.

Asked how long it will take to liberate the western side of the city, al-Abadi said: 'I can't tell now, but we are capable of doing so and we will do so.'

The United Nations Assistance Mission for Iraq (UNAMI) on Saturday urged the Iraqi government to launch investigations into the video report

Hundreds of civilians fled from the northeastern Rashidiya neighborhood on foot as Iraqi helicopters circled overhead and fired on militants. At least two wounded Iraqi soldiers were brought back from the front lines after a suicide bombing.

A mortar attack in another neighborhood in eastern Mosul killed an Iraqi army colonel on Sunday, according to Brig. Gen. Yahya Rasool, a military spokesman.

Meanwhile, Al-Abadi renewed his promise to investigate allegations of human rights violations by security forces in conflict areas and bring those responsible to trial.