Elite Iraqi forces on Thursday retook a town on the eastern edge of Mosul while Kurdish peshmerga opened a new front in the offensive to wrest back the jihadists' last bastion in Iraq.
Prime Minister Haider al-Abadi told an international meeting in Paris that the four-day-old offensive was "advancing faster than expected".
France and Iraq were co-chairing the meeting on the future of Mosul, which observers have warned could raise even greater humanitarian and inter-confessional challenges than the massive military operation to retake it.
In some areas, the Iraqi advance was met by a trickle of civilians fleeing both the fighting and the jihadists who ruled them for two years, but the feared mass exodus from Mosul had yet to materialise.
The counter-terrorism service, Iraq's best-trained and most battle-seasoned force, retook full control of Bartalla, a town that lies less than 15 kilometres east of Mosul.
"I announce to the people of Bartalla and Mosul we have complete control over Bartalla," CTS commander Taleb Sheghati al-Kenani told reporters from the town.