The Telegraph's Mike McGrath says the fee for the 20-year-old Serbian will be €8million (£6.8m), plus add-ons.
Ilic played for the Italian club on loan last season after joining the Citizens from Red Star Belgrade in 2017, one of four loan spells since signing and making no City appearances.
He has just joined Verona on-loan this summer, but is now set to see his deal converted to a permanent transfer.
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