Already in control of eastern Mosul, Iraqi forces have now cut off road access to the west.
It means that ISIL fighters are trapped in what remains of the city that was the group’s biggest stronghold in its cross-border, self-declared caliphate.
Meeting government figures in Baghdad, Brett McGurk, the United States’ envoy to the coalition against so-called Islamic State, said jihadists still in Mosul will die.
“ISIS has now lost over 60 percent of the territory it once held here in Iraq and is losing more every day,” McGurk told reporters in the Iraqi capital on Sunday.
“In total, in Iraq and Syria, coalition-enabled operations – that means our coalition supporting local partners, including Iraqi security forces – have cleared 50,000 square kilometres of territory from ISIS.”
According to one commander, Iraqi forces have now recaptured a third of western Mosul from ISIL.
But the battle has uprooted men women and children from the densely-populated west where the extremists are putting up fierce resistance using suicide car bombs, snipers and mortars.
More than 215,000 people are currently internally displaced from Mosul and surrounding areas following the military operations which began in October 2016, according to the UN refugee agency, UNHCR.
The UNHCR says thousands of people are arriving daily at the already packed Hamam Al-Aleel screening site, where they undergo a last round of security screening before being moved to camps or host communities.
Up to 600,000 civilians remain trapped with the militants.
More evidence has emerged meanwhile of war crimes, including a mass grave.
Witnesses have told how hundreds of mainly Shi’ite inmates were shot dead when the Sunni Islamist fanatics overran the Badush prison near Mosul in June 2014.