Bartella, a historically Christian town 15 kilometers (9 miles) to the east of Mosul, was retaken by Iraqi special forces lasat week.
Armoured vehicles and artillery pieces were seen at the Bartella frontline east of Mosul, AP reports.
The Mosul operation is expected to be the most complex yet for Iraq's military, which is still rebuilding from the humiliating defeat it suffered when the city fell to ISIS (ISIL , IS , Daesh) more than two years ago.
The campaign to retake Mosul comes after months of planning and involves more than 25,000 Iraqi troops, Kurdish forces, Sunni tribal fighters and state-sanctioned Shiite militias.
It is expected to take weeks, if not months, to drive ISIS out of Iraq's second largest city, which is still home to more than a million people.
Haider al-Abadi, the Iraqi prime minister, has promised that Mosul would be liberated by the end of the year.
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