Iraqi forces thrust north from the Euphrates Valley into the desert on Saturday, opening up a new front in the drive to flush out fugitive ISIS militants, a commander said.
ISIS has already been driven from all the towns it once held, but Prime Minister Haider al-Abadi has said he will not proclaim victory until the militants have been cleared from the western desert bordering Syria.
Troops and paramilitaries had advanced into the desert from the east and north on Thursday at the start of an offensive aimed at inflicting a final defeat on the terrorist group.
On Saturday, troops and tribal militia pushed north from Al-Qaim and Rawa, two Euphrates Valley towns recaptured from ISIS earlier this month, in a pincer movement against retreating militants, one of the operation's two commanders told AFP.
"It's a matter of linking up with the forces advancing from Nineveh" province in the north, the commander said, asking not to be identified.
"The aim of the operation is to clear the desert right up to the Syrian border and hunt down the terrorists who fled into the desert from the towns that have been liberated."
At the peak of its power in 2014, ISIS ruled over seven million people in a territory encompassing large parts of Syria and nearly a third of Iraq.
It is now being flushed out of its last desert hideouts in Iraq at the same time as its final pockets of control in Syria face simultaneous operations by Russian-backed government forces and US-backed Kurdish-led fighters.