Iraqi forces launched an offensive on Saturday to retake the last pocket of territory in the country still held by the Islamic State group, the operation's commander said.
The Euphrates valley town of Rawa and nearby villages were bypassed by government troops and allied militia when they retook the Syrian border town of Al-Qaim last week.
Troops backed by militia recruited among the region's Sunni Arab tribes "launched a major offensive to liberate Rumana and the Rawa area,", General Abdelamir Yarallah said.
Rumana is on the north side of the Euphrates just across from Al-Qaim while the small town of Rawa lies downstream.
Rawa is the last town still held by IS apart from Albu Kamal, Al-Qaim's twin town just across the Syrian border where the jihadists were still battling Damascus troops and allied forces on Saturday after mounting a surprise counterattack late Thursday.
The Syrian army had declared victory in the battle for Albu Kamal but IS fighters pushed back in from the desert to the north where they still control a strip of territory between areas held by government troops and by US-backed Kurdish-led forces.
The recapture of the Rawa pocket would mark the final battleground defeat of IS in Iraq and sound the death knell of the sprawling "caliphate" the group declared in 2014 over a swathe of Iraq and Syria the size of Britain.