BAGHDAD (Reuters) - When Iraqi Prime Minister Haider al-Abadi took office, he was regarded as a moderate Shi'ite leader who could win over powerful Sunni tribal chiefs to the fight against Islamic State.

Three months later, Sunnis who once helped U.S. Marines kick the Islamic State's predecessor al Qaeda out of Iraq view Abadi with deep scepticism because he has yet to deliver on promises to support their neglected Sunni heartland Anbar province.