Iraqi forces launched on Thursday an offensive to recapture the last patch of Iraqi territory still in the hands of Islamic State, on the border area with Syria, Prime Minister Haider al-Abadi said.
"Daesh members have to choose between death and surrender," he said in a statement announcing the offensive on region of al-Qaim and Rawa.
The Iraqi air force dropped thousands of leaflets on the border area calling on the militants to surrender and urging the population to stay away from their positions, according to a statement from the Joint Operations Command in Baghdad.
The militant group also holds parts of the Syrian side of the border, but the area under their control is shrinking as they retreat in the face of two sets of hostile forces - a US-backed, Kurdish-led coalition and Syrian government troops with foreign Shi'ite militias backed by Iran and Russia.
Islamic State's self-declared cross-border caliphate effectively collapsed in July, when US-backed Iraqi forces captured Mosul, the group's de facto capital in Iraq, in a grueling battle which lasted nine months.
The militants' Syrian stronghold, Raqqa, fell to US-backed forces last week.
Islamic State leader Abu Bakr al-Baghdadi, who declared the caliphate from Mosul in mid-2014, released an audio recording on Sept. 28 that indicated he was alive, after several reports he had been killed. He urged his followers to keep up the fight despite setbacks.
"Tell those among your children and relatives who took up a weapon against the state to throw it aside immediately, and to go to any house on top of which a white flag have been raised when the liberation forces enter al-Qaim,'' said the leaflets dropped by the Iraqi air force.
Regular army units, Sunni tribal forces and Iranian-backed Popular Mobilization are taking part in the offensive toward the Syrian border, the Joint Operations Command said.