ISIS ringleader Abu Bakr al-Baghdadi is reportedly seriously ill after having his food poisoned by an assassin, Daily Mail said.

Meals prepared for the ISIS leader and three other commanders of the terrorist organisation were allegedly poisoned in the Be'aaj district, southwest of Nineveh.

A source told Iraqi news agency WAA the four are suffering from 'severe poisoning' and 'have been transferred to an unknown location under strict measures.'

The terror group have reportedly launched a campaign of arrests to track down those responsible, the Daily Mail report further said.

Baghdadi is credited with transforming the breakaway al-Qaeda group turning it into the independent ISIS group that is arguably the most powerful and wealthiest jihadist organisation in the world.

Under his leadership, the group spearheaded a militant offensive that expanded into Syria in 2013 and which later overran much of Iraq's Sunni Arab heartland.