An Iraqi helicopter flies over military vehicles in Husaybah, in Anbar province
An Iraqi helicopter flies over military vehicles in Husaybah in Anbar province, 22 July 2015 Reuters

The Iraqi army and tribal forces have captured the first outlying villages in the western Anbar province as the US backed forces enter the second day of their assault on Islamic State (Isis) territory held along the Syrian border.

Commander of Sunni Tribal Forces, Nathim al-Jaghifi said in a statement that 25 miles of territory west of the government-held town of Haditha had been captured by the anti-IS forces.

The offensive south of the major Iraqi assault on Mosul began on Thursday (5 January 2017) with the intention of dislodging IS from Rawa, Ana and al-Qaim. The three towns lie along the militant group's former supply route into Iraq from Syria.

AFP reported the army's seventh division, police, and fighters from tribes opposed to Isis in their local area had been brought into the offensive, backed by US airpower.

"Our forces started advancing from Haditha towards Ana from several directions," Lieutenant General Qassem Mohammedi, commander of operation was quoted saying.

Although Iraqi forces retook the principal IS-held towns of Ramadi and Fallujah from Isis in 2016, Isis has remained ensconced in western Anbar in the Sunni areas, the first the militant group captured when it crossed from Syria in the summer of 2014.

As the assault by Iraqi forces began, Reuters reported that IS attacked an Iraqi army outpost and a police station near the city of Tikrit, 109 miles behind the frontline in Anbar.

Isis used a car bomb and two suicide attackers in their assault shortly after midnight in an assault on the town of al-Dour on Tikrit's outskirts involving two police officers and two soldiers, military sources were quoted as saying.

The Iraqi assault on Mosul has continued into its fourth month with renewed fighting following a relative lull. Elite Iraqi troops have continued their advance against the militants in recent days, pushing IS back across a tributary of the Tigris river shortly after midnight.