ISIS has finally admitted its leader Abu Bakr al-Baghdadi is dead, according to reports in Iraq.

The terror group is said to have confirmed that the 45-year-old was killed in an air strike in the Iraqi province of Nineveh.

Reports claim ISIS fanatics are scrambling to find a successor to the terror chief, who announced the formation of the group's so-called caliphate in Mosul in 2014.

A ban on jihadis talking about the leader's death has now been lifted, according to a source who spoke to Iraqi media.

If confirmed, his death would mark another devastating blow to the jihadist group after its loss of Mosul, which Iraqi Prime Minister Haider al-Abadi said Monday had been retaken from ISIS after a gruelling months-long campaign.

ISIS has finally admitted its leader Abu Bakr al Baghdadi is dead, according to media reports in Iraq

A photo shared by the Russian Defense Ministry claimed to show the site where ISIS leader Abu Bakr al-Baghdadi was killed. The aerial image (left) of the ISIS headquarters is seen on May 13, 2017, and an aerial image taken on May 29 (right), shows the same site following the Russian airstrike on May 28 on the outskirts of Raqqa

The Syrian Observatory for Human Rights war monitor said today that it also had information from top ISIS group leaders confirming the death.

'Top tier commanders from IS who are present in Deir Ezzor province have confirmed the death of Abu Bakr al-Baghdadi, emir of the Islamic State group, to the Observatory,' director Rami Abdel Rahman told AFP.

'We learned of it today but we do not know when he died or how.'

The Pentagon said today that it had no information to corroborate the claims.

'We take any report of this nature with a large dose of salt,' Sebastian Gorka, deputy assistant to President Donald Trump, told Fox News.

'We will verify it. We will look at the intelligence available ... and we will give a statement when we have the requisite facts.'

Coalition spokesman Colonel Ryan Dillon added: 'We cannot confirm this report, but hope it is true.

'We strongly advise ISIS to implement a strong line of succession, it will be needed,' he added.

There was no official confirmation or denial of the news on social media platforms used by ISIS.

Russia's army said Sukhoi warplanes carried out a 10-minute raid on May 28 at a location near the ISIS stronghold of Raqqa, where group leaders had gathered to plan a pullout from the area.

Reports of al-Baghdadi's death come as pictures show airstrikes on ISIS positions on the edge of Mosul's Old City today

Members of the Iraqi federal police forces celebrate in the Old City of Mosul last night

The US-led coalition fighting the jihadist group in Syria and Iraq said at the time it could not confirm whether the Russian strike had killed Baghdadi.

The Iraqi-born leader of ISIS has not been seen in public since making his only known public appearance as 'caliph' in 2014 at the Grand Mosque of Al-Nuri in Mosul.

ISIS destroyed the highly symbolic site before Iraqi forces could reach it as they pushed the jihadist group from Mosul, where Iraq's government formally declared victory on Monday.

With a $25-million US bounty on his head, Baghdadi has kept a low profile and was rumoured to move regularly throughout ISIS-held territory in the area straddling Iraq and Syria.

His death, if confirmed, would be a new blow to the group which is also battling a US-backed coalition of Kurdish and Arab fighters for control of its Syrian stronghold Raqqa.

Earlier this month, an ISIS preacher and leader was executed by the militants after he accidentally suggested that al-Baghdadi had died.

Abu Bakr Al-Baghdadi has not been seen since declaring the creation of the Islamic State in July 2014

Senior ISIS leader and preacher, Abu Qutaiba was burned to death in the group's stronghold town of Tal Afar, Alsumaria News reported.

In January it was reported the leader had been 'critically injured in airstrikes in northern Iraq.'

The Pentagon said in December it believed that the ISIS chief was alive, despite repeated efforts by the US-led coalition to take out the jihadist group leader.

Baghdadi was born Ibrahim Awad al-Samarrai in 1971 in Tobchi, a poor area near Samarra, north of the capital Baghdad.

His family included preachers from the ultra-conservative Salafi school of Sunni Islam, which sees many other branches of the faith as heretical and other religions as anathema.

He joined the Salafi jihadist insurgency in 2003, the year of the U.S.-led invasion of Iraq, and was captured by the Americans. They released him about a year later, thinking he was a civilian agitator rather than a military threat.

It was not until July 4, 2014, that he seized the world's attention, climbing the pulpit of Mosul's medieval al-Nuri mosque in black clerical garb during Friday prayers to announce the restoration of the caliphate.

Thousands of volunteers flocked into Iraq and Syria from around the world to become "Jund al-Khilafa", or soldiers of the caliphate.

At the height of its power two years ago, Islamic State ruled over millions of people in territory running from northern Syria through towns and villages along the Tigris and Euphrates river valleys to the outskirts of the Iraqi capital Baghdad.

It claimed or inspired attacks in dozens of cities including Paris, Nice, Orlando, Manchester, London and Berlin, and in nearby Turkey, Iran, Saudi Arabia and Egypt.

In Iraq, it staged dozens of attacks targeting Shi'ite Muslim areas. A truck bomb in July 2016 killed more than 324 people in a crowded area of Baghdad, the deadliest attack since the 2003 invasion of Iraq.

The loss of Mosul and the siege of Raqqa, Islamic State's capital in Syria, by a U.S.-backed, Kurdish-led force stripped Baghdadi of the trappings of caliph and made him a fugitive in the desert border area between the two countries.