Izzat Ibrahim al-Douri,who was late Iraqi leader, Saddam Hussein's former right-hand man has been reportedly killed.
Iraqi media reports that he died near the northern town of Hamreen in Irbil province.
The 72-year old led the Naqshbandi Order, one of the main insurgent groups in Iraq and a key force behind the recent rise of Islamic State (IS).
BBC reports that he was regarded as the most high-profile official of Saddam Hussein's Baath party to successfully evade capture after the United States Iraqi invasion, and had a large bounty on his head for years.
While there have been reports of al-Douri's death or capture before, correspondents says this is the most credible so far.
The US has led Iraqi forces to seize large areas from ISIS and its allies in recent months.