The Iraqi army says around 50 villages have been liberated since Monday
Intense fighting is continuing as coalition forces push closer to Islamic State's last major stronghold of Mosul.
Troops have retaken a Christian region, including the town of Bartella, as they edged toward Iraq's second biggest city.
Around 50 villages have been liberated since Monday, according to the Iraqi army.
Kurdish Peshmerga forces are understood to be planning to stop along a line at an average of 12 miles outside Mosul and a US military official said on Saturday that the troops were "pretty much there".
Elite federal forces are then expected to lead the breach on the city.
However, progress has been hampered by a toxic cloud from by a fire started by IS fighters at a sulphur plant south of Mosul.
It has killed at least two civilians and forced some American personnel taking part in the US-backed operation to wear protective masks.
A local health centre said it had treated 500 people complaining of breathing problems.
A senior interior ministry officer in Qayyarah, a main staging base south of Mosul, said: "Of course, this is affecting our planned progress."
Meanwhile, Kurdish forces are also engaged in a huge push around the Islamic State-held town of Bashiqa, northeast of Mosul.
They gained significant ground in the early days of the offensive, which launched on October 17th.
US Secretary of Defence Ashton Carter praised them for "the way their efforts are completely coordinated with the Iraqi security forces".
He said the fight for Mosul was "on track and on schedule".
More than 30,000 troops are involved in the mission to retake the city. A key concern is for the safety of up to 1.2 million civilians in Mosul, who are trapped by the fighting.
According to residents, living conditions are deteriorating daily, with food shortages and IS paranoia of informants mounting.
The United Nations has said Mosul could need the biggest humanitarian relief operation in the world once it has been liberated.
The interior minister of the Kurdish regional government, Karim Sinjari, said there were reports of people in Mosul rising up against IS and carrying out nighttime attacks.
He also claimed Islamic State's leader, Abu Bakr al Baghdadi, had been in Mosul to try and rally the thousands of fighters who control the city.
Jihadists have been launching dozens of suicide car bombs against advancing forces, inflicting casualties and slowing their advance.
The hunt is also continuing for surviving militants who carried out a fierce raid on the Iraqi city of Kirkuk in an attempt to divert attention from the offensive to win back Mosul, 105 miles away.
Some 46 people - mostly from the security services - were killed in the fighting, according to the interior ministry. More than 130 were wounded.
The Kirkuk police chief said 48 attackers had also been killed and several others wounded.
Brigadier General Khattab Omer said: "The security forces control the situation now but there are still pockets of jihadists in some southern and eastern neighbourhoods."
IS controlled more than a third of Iraq two years ago, but its self-proclaimed caliphate has been shrinking steadily.