Speculation has swirled over the fate of the leader of the Islamic State in Iraq and Syria (ISIS) after reports that he was killed or wounded in US-led air strikes.

Although the ISIS has released an audio recording that it said was of Abu Bakr al-Baghdadi, officials in both Iraq and the United States say no one is yet certain about the fate of the ISIS leader.

Here's a look at the man who is said to be the most dreaded terrorist of our times:

Unknown and enigmatic

The self-proclaimed caliph terrorising Iraq and Syria is a preacher who rose from obscurity to lead the world's most feared extremist organisation. Little is known about Abu Bakr al-Baghdadi, whose aliases, according to US intelligence, include Abu Dua and Dr Ibrahim Awwad Ibrahim Ali al-Badri al-Samarrai.

Baghdadi, who is believed to be born in Samarra in Iraq in 1971, claims his descent from Prophet Mohammed and has a doctorate in Islamic studies. In a picture released this year by Iraq, Baghdadi appears as a balding, bearded man in a suit and tie.

Path to insurgency

Baghdadi apparently joined the insurgency that erupted shortly after the 2003 US-led invasion of Iraq. Reports suggest he was a cleric in a mosque in Samarra around the time of the invasion. Some believe he was radicalised during the four years he was held at Camp Bucca, a US facility in southern Iraq where many Al-Qaeda commanders were detained.

He took the reins of what was then known as the Islamic State of Iraq (ISI) in May 2010 after two of its chiefs were killed in a US-Iraqi raid.

In October 2011, the US Treasury designated him as a "terrorist", and there is now a US$10-million (S$12 million) bounty for his capture.

Claim to infamy

Baghdadi was declared a caliph on June 29, 2014 in an attempt to revive a system of rule that ended nearly 100 years ago with the fall of the Ottoman Empire, and ordered Muslims to obey him in a video from the northern city of Mosul. He revived the fortunes of Iraq's struggling Al-Qaeda affiliate, turning it into the independent ISIS group, arguably the most brutal, powerful and wealthiest extremist organisation in the world.

Under his leadership, ISIS spearheaded a militant offensive that overran much of Iraq's Sunni Arab heartland since June after seizing major territory in neighbouring Syria, and carried out a series of atrocities in both countries.

The group has killed hundreds of Iraqi and Syrian tribesmen who opposed it, attacked members of the Yazidi religious minority, sold women as slaves, executed scores of Iraqi security personnel and beheaded western journalists and aid workers on camera.

Clout of the Commander

When Baghdadi took over ISI in April 2010, it appeared to be on the ropes after the surge of US forces combined with the shifting allegiances of Sunni tribesmen to deal it a blow. But the group bounced back, expanding into Syria in 2013.

Baghdadi sought to merge with Al-Qaeda's Syrian franchise, Al-Nusra Front, which rejected the deal, and the two groups have mostly operated separately since.

But ISIS received a major boost this week from Egypt when the country's deadliest militant group, Ansar Beit al-Maqdis, pledged allegiance to Baghdadi.

Baghdadi is touted within ISIS as a battlefield commander and tactician, a crucial distinction compared with Al-Qaeda chief Ayman al-Zawahiri, and has attracted legions of foreign fighters, estimated to be in the thousands, as well as supporters from around the world who distribute the group's propaganda online.

SOURCE: BBC, AFP