BAGHDAD - 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 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 militants 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.
IS has cost Iraq 'more than $100b
The Islamic State group's occupation of northern Iraq and the battle to defeat it has caused more than $100 billion worth of damage, Prime Minister Haider al-Abadi said Saturday.
He was speaking during a visit to Karbala, where millions of pilgrims gathered Friday to mark the annual Arbaeen commemoration.
"The damage caused by the IS occupation of Iraqi cities already amounts to more than $100 billion," Abadi said.
"That's just the damage to the economy and infrastructure."
IS, a radical group, seized around a third of Iraq and parts of Syria in a sweeping 2014 advance.
But its self-declared "caliphate" has since been decimated by multiple offensives and squeezed into a pocket of territory on the Iraqi-Syrian border.
Iraqi forces launched an operation Saturday to retake the last IS-held towns in Iraq, including the Euphrates valley town of Rawa and nearby villages.
The assault also aims to "clean open areas in the desert" of western Iraq, said Abadi, who is also head of the armed forces.
Mass graves holding '400 IS victims' found
Mass graves containing at least 400 suspected Islamic State group victims have been found near the former militant bastion of Hawija in northern Iraq, the regional governor said Saturday.
The string of grisly discoveries was made at a military base around three kilometres (two miles) from the city that the militants "turned into an execution ground", Kirkuk governor Rakan Said said.
"Not less than 400 people were executed," he said, adding that some were clad in the uniform of prisoners condemned to death while others wore civilian clothing.
IS was forced out of Hawija - 240 kilometres north of Baghdad - by Iraqi forces in October in a sweeping offensive that has seen the group lose the vast bulk of territory it seized in 2014.
As government troops have advanced across Iraq they have uncovered dozens of mass graves holding hundreds of bodies in areas that fell under the militants' brutal rule.
The burial pits near Hawija were discovered "thanks to witness accounts from local residents" given to the Iraqi military, General Mortada al-Luwaibi said.
Saad Abbas, a farmer from the area, told AFP that during the three years of IS control the group's fighters could be seen "driving around in cars with their prisoners".
"They would shoot them and then throw them to the ground or burn their bodies," Abbas said.