He has long been feared by his ISIS enemies and now Abu Azrael has re-emerged on the frontline in Iraq and has vowed to 'pulverise' some more takfiri militants.

Nicknamed the 'father of archangel of death' in Arabic, Abu Azrael is the poster boy of the Imam Ali brigade, an Iraqi Shi'a militia group fighting against ISIS terrorists.

Now the celebrity militant has been spotted participating in the Iraqi forces push to re-capture the ISIS-held city of Fallujah.

The bald fighter was filmed using a large machine gun near the city, which has been heavily besieged by Iraqi government and paramilitary forces.

Abu Azrael appears to be have ditched his famous axe, which he was often photographed carrying onto the battlefield.

Other photos have previously shown the colossal warrior carrying a large sword, fearlessly wandering through the battlefield.

As well as posing with his weapons, Abu Azrael also appears to love a selfie and posting short videos of him and his friends relaxing after battle.

Well known for his sense of humour, one video shows Abu Azrael using a captured ISIS walkie-talkie to taunt and mock the depraved savages of ISIS.

The fighter appears to enjoy giving an insight into his life as a soldier. Previous videos have shown the Iraqi soldier cycling through parts of the Iraqi city of Tikrit.

Another video shows the towering fighter wandering around a captured ISIS bases, taking time to cheekily steal a teapot.

A multitude of stories were claimed about the background of Abu Azrael. Some reports even claim he was once Iraq's national champion in Taekwondo.

It is possible he was motivated to join the fight after a representative of Grand Ayatollah Ali al-Sistani issued a call to arms in Friday prayers in mid June 2014.

Determined to defend his home and country, Abu Azrael joined the Imam Ali brigade, an Iraqi Shi'a militia.

The militia has previously been seen fighting alongside the Iraqi army in the re-capturing of the Iraqi city of Tikrit.

With the arrival of the Iraqi Rambo, morale is high among the Iraqi Shi'a militias, who appear confident in ridding ISIS from Iraq.

The United Nations has revised significantly upward the number of civilians believed trapped in besieged Falluja, an ISIS stronghold near Baghdad, to possibly 90,000 from a previous estimate of 50,000.

In a telephone interview with Reuters in Baghdad, U.N. Humanitarian Coordinator for Iraq Lise Grande for Iraq warned that the civilians could face a 'harrowing' situation in the besieged city 50 kilometers (32 miles) west of Baghdad.

The Iraqi army began an offensive to dislodge the insurgents from Falluja on May 23, but the city has been under a de facto siege, with no supplies getting in, for about six months.

'We have underestimated how many civilians are in Falluja,' Grande said. 'People who are coming out are giving us the strong impression that we could be talking about maybe 80,000 to 90,000 civilians that are inside;' Abna reported.

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