A senior Iraqi general has called on Iraqis fighting for Islamic State in Mosul to surrender as a wide-scale operation to retake the militant-held city entered its third day.
Lt Gen Talib Shaghati told reporters at a military base that up to 6,000 IS fighters are inside the city. He did not say how many of them are foreigners.
IS captured Mosul, Iraq's second largest city, in a lightning advance in the summer of 2014.
The extremist group has suffered a string of defeats over the past year and Mosul is its last major urban bastion in Iraq.
So far, the militants have put up fierce resistance in villages surrounding the city, where most of the fighting has been concentrated.
IS has sent trucks loaded with explosives towards the front lines and fired mortars to slow the Iraqi forces' advance.
An Iraqi officer from the 9th Division said his troops were now around one kilometre (half a mile) away from Hamdaniyah, a historically Christian town also known as Bakhdida, to the east of Mosul.
Over the past day, IS sent 12 car bombs, all of which were blown up before reaching their targets, he said, adding that Iraqi troops suffered a small number of casualties from the mortar rounds.
To the north, air strikes pounded Bashiqa as Kurdish forces fired mortar rounds from an area overlooking the IS-held town.
Save the Children said 5,000 people have fled to a refugee camp in north-eastern Syria from the Mosul area in the last 10 days, with another thousand waiting to enter at the border.
The group said the overwhelmed camp is "littered with waste and faeces, with a looming risk of outbreaks of disease".
It said there are just 16 toilets shared by more than 9,000 people, many of whom only have access to dirty, untreated water.
"Conditions there are among the worst we've seen, and we expect thousands more people to be on their way soon," said Tarik Kadir, head of the group's Mosul response.
The top commander of US land forces in Iraq says US army Apache attack helicopters are striking IS targets in support of the push to retake Mosul.
Adding US attack helicopter crews to the unfolding combat is an extra element of risk for American troops.
Major General Gary Volesky said the Apaches were being used at night to strike targets from a distance.
He said the mere presence of the Apaches was a confidence booster for Iraqi soldiers.
Maj Gen Volesky, commanding general of the 101st Airborne Division, said he believes IS fighters in Mosul will put up a stiff defence in the city but eventually lose and morph into an insurgency.
The operation to retake Mosul is the largest launched by the Iraqi army since the 2003 US-led invasion.
Some 25,000 troops, including Sunni tribal fighters, Kurdish forces known as the peshmerga and state-sanctioned Shiite militias known as the Popular Mobilisation Units are approaching the city from different directions.
The participation of the Shiite militias in the operation to retake the mainly Sunni Mosul has raised concerns that the campaign could inflame sectarian tensions.
Rights groups have accused the Shiite militias of abuses in past campaigns against IS-held areas.
In a bid to alleviate those concerns, Shiite militia leaders announced that they will only focus on capturing the mostly Shiite town of Tal Afar to the west of Mosul, and not enter the city itself.
"The only troops who will enter Mosul are the army and police, not the Popular Mobilisation Units or the peshmerga," said Hadi al-Amiri, the leader of the Badr Brigade, one of the largest Shiite militias.
"This has been agreed upon," he said at a press conference in the Shiite holy city of Najaf.
Amnesty International said in a report released on Tuesday that Iraqi government and paramilitary forces detained, tortured or killed hundreds of Sunni Arab civilians fleeing IS-held areas during the operation to retake the Sunni city of Fallujah, west of Baghdad, earlier this year.
The Iraqi government has denied any systematic violations by security forces or the militias, and says individuals have been held accountable for occasional abuses.