“It’s a matter of a few days and we will announce the total liberation of Mosul,” Abadi told reporters on Thursday, according to Baghdad-based Sumaria TV.
The announcement came as Iraqi forces were continuing the fight against ISIL fighters in their last stronghold in western Mosul, the city’s old town.
Footage obtained by the Associated Press news agency showed Iraqi forces pushing into the Bab al-Beed neighbourhood in Mosul’s Old City – the last ISIL stronghold in what appears to be the final major Iraqi battle.
The armed group have lost much of their territory over the past three years, and Mosul is their last urban bastion in Iraq.
The group’s fighters are expected to make their last stand in the Old City – a densely populated quarter with narrow, winding alleys.
Up to 150,000 civilians are believed to be trapped in there, where conditions have been described by the UN as desperate.
The fight for Mosul has now lasted for more than eight months.
On Wednesday, ISIL fighters blew up Nuri mosque as Iraqi forces advanced on the ancient religious compound in the embattled northern city.
Officials from Iraq and the US-led anti-ISIL coalition said the destruction of the site was a sign of ISIL’s imminent loss of Mosul, with Iraqi Prime Minister al-Abadi calling it an “official declaration of defeat”.
The loss of the iconic 12th-century minaret – one of the country’s most recognisable monuments sometimes referred to as Iraq’s Tower of Pisa – left the country in shock.