Iraqi government and paramilitary forces announced Friday plans to launch an assault to retake Hawija, the last Islamic State group's urban bastion in the country, a day after recapturing Tal Afar.

Iraqi forces have now forced IS out of all its Iraqi territories except the town of Hawija, 300 kilometres (190 miles) north of Baghdad, and three pockets of territory near the border with Syria.

On Thursday, Prime Minister Haider al-Abadi announced the recapture of Tal Afar town and its surrounding areas, weeks after ousting the jihadists from Iraq's second city Mosul, bringing all of Nineveh province under government control.

"After the Tal Afar mission was successfully accomplished, the troops will head to Hawija," in oil-rich Kirkuk province, Iraq's Joint Operations Centre (JOC) said in a statement.

A spokesman for the Hashed al-Shaabi paramilitary group, dominated by Iran-backed Shiite militias, told AFP the offensive could be launched very soon.

"The operation to liberate Hawija will begin a few days after Eid al-Adha," spokesman Ahmed al-Assadi, said referring to the Muslim holiday marking the end of the annual hajj pilgrimage to Mecca in Saudi Arabia.

Sunni Muslims began observing Eid al-Adha on Friday, while Iraqi Shiite Muslims will mark the start of the four-day holiday on Saturday.

The JOC said Iraqi aircraft have dropped "millions of leaflets" on Hawija to inform residents that the rule of "the terrorist gangs of IS will soon be over".

Residents were urged to "keep away" from jihadists who could become the target of air strikes by Iraqi forces backed by the US-led coalition.

The leaflets also called on the jihadists to "surrender and give up their weapons".

Assadi said the operation aimed at retaking from IS an area of 9,000 square kilometres (3,500 sq miles), covering the town of Hawija and surrounding the area, including eastern Shargat, a town further west.