The Iraqi army has closed in on the centre of Shirqat, a northern town held by ISIL seen as a stepping stone in a military campaign to recapture the armed group's stronghold of Mosul.
The army, backed by local police and tribal fighters, took 12 nearby villages since launching the operation on Tuesday morning, Ali Dawdah, the mayor of Shirqat currently based in Erbil, said on Wednesday.
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With air support from a US-led coalition, the troops are now less than 3km from the town centre, according to Dawdah, who said he expected the campaign to be concluded within 48 hours.
Five security personnel and one civilian were killed in the battle for Shirqat, said the mayor.
The town lies on the west bank of the River Tigris in Salaheddin province, 260km northwest of Baghdad and around 80km south of Mosul.
"We are making good progress," Yahya Rasool, Joint Operations Command spokesman, told AFP news agency earlier on Wednesday.
"Shirqat is important," he said. "We can't move on Mosul and have terrorists control Sherqat."
Tens of thousands of civilians are thought to be trapped in Shirqat and surrounding villages, which have been under the control of the Islamic State of Iraq and the Levant (ISIL, also known as ISIS) since the group seized a third of Iraqi territory in 2014.
Officials have warned for months of a humanitarian disaster inside the town, with residents facing food shortages.
There has not been a large-scale displacement of civilians so far.
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Residents of Shukran and Houri villages told Reuters news agency by phone that they had begun waving white flags above their houses on Tuesday evening as the military advanced, but ISIL punished them with 50 lashes each.
'Mosul push in October'
Meanwhile, a top US official said on Wednesday that the push on Mosul could begin as early as next month.
"We assess today that the Iraqis will have in early October all the forces marshalled, trained, fielded, equipped that are necessary for operations in Mosul," US General Joe Dunford, chairman of the Joint Chiefs of Staff, said at a military event in Washington.
"Timing of that operation now is really just a function of a political decision by Prime Minister [Haider al-]Abadi."
Though the Pentagon does not plan on directly sending US troops into combat, it has thousands of soldiers in Iraq who are training and arming Iraqi partners.
"We will be in a position to provide whatever support, whatever reinforcement, those forces need in order to be successful," Dunford said.
ISIL seized Mosul in a lightning offensive through the north and west of the country, in 2014.
Mosul had an estimated population of around two million before ISIL took it over.
Accurate numbers for the population remaining in the city are hard to come by but the United Nations and other officials have said up to one million civilians may still be living under ISIL rule in the Mosul area.
The Pentagon estimates 3,000 to 4,500 ISIL fighters are in Mosul.
Source: News Agencies