The leader of Isis has been reportedly killed as Kurdish-led anti-Isis forces, backed by US firepower, begin the final assault on Raqqa, in Syria.

According to reports from Syrian state TV, the world's most wanted terrorist, Abu Bakr al-Baghdadi, is said to have been killed on Saturday when he was caught in a heavy artillery barrage on Raqqa, the de facto capital of Isis, though the reports are yet to be verified.

This isn't the first time that the extremist leader, who has a $25m bounty on his head, has been reported dead, so the news has been met with scepticism. The terrorist organisation's media arm Amaq has not yet confirmed the reports.

At least seven civilians were reported to have been killed in Saturday's air strikes, according to independent Syrian news platform Raqqa24, but as yet there is no mention of the Isis leader.

In March, US Secretary of State Rex Tillerson vowed to assassinate al-Baghdadi. He issued the threat to the Isis kingpin, saying that his deputies had been wiped out and it was "only a matter of time before Baghdadi meets this same fate".

In February 2017 at least 13 Islamic State (Isis) commanders were killed in air strikes in western Iraq targeting a house where it was believed al-Baghdadi was meeting with other militants.

Reports have regularly emerged from various sources in the Iraqi media and from some Western outlets claiming Baghdadi's death. They have never been substantiated.

In December 2016 the Pentagon stated they believed the Isis leader was alive and still giving orders through his commanders. In mid-December, the US announced an increase in reward for capturing or killing Baghdadi to $25m (£20.3m).

In November, Isis released an audio message, purportedly from Abu Bakr al-Baghdadi, in which he called on his fighters not to retreat in Mosul as Iraqi forces ready themselves for a final assault on the city.

Baghdadi was born in Samarra, Iraq, in 1971 and reportedly joined the extremist movement in 2003 following the US invasion of Iraq.

The hate preacher has not been seen in public since carrying out a sermon in Mosul's Great Mosque of al-Nuri July 2014.