Over 28,000 people have fled since the start of a drive to retake west Mosul, as Iraqi forces closed in Wednesday on a road linking the city with a jihadist-held town to the west.
West Mosul is the largest population centre still controlled by the Islamic State group, and its recapture would mark the effective end of the cross-border "caliphate" leader Abu Bakr al-Baghdadi announced from a mosque in the city more than two years ago.
Iraqi forces have yet to advance deep into west Mosul but fighting combined with privation and harsh IS rule is pushing a growing number of civilians to flee.
"The humanitarian impact has been significant. Since the new offensive began, 28,400 people have been dispaced from west Mosul," the United Nations office coordinating the Mosul humanitarian response said in a statement, citing International Organization for Migration figures.
"Since 25 February, approximately 4,000 people per day have been displaced," it said.
The number who have fled is still only a fraction of the 750,000 people who are believed to have stayed on in west Mosul under IS rule but it is expected to rise sharply in the coming days and weeks.
Iraqi forces are fighting inside west Mosul, but have also moved through the surrounding desert to cut the area off from the IS-held town of Tal Afar to its west.
On Wednesday, Staff Lieutenant General Qassem al-Maliki, the commander of the 9th Armoured Division, said his forces were in effective control of the Mosul-Tal Afar road, which would help isolate the jihadists in west Mosul.
"We control the road by fire," Maliki said, explaining that while his forces had not reached it, they can fire on targets on the route.
But their ability to do that will likely be reduced at night, and jihadists may still be able to use other routes to move in and out of the city.
A commander in the elite Counter-Terrorism Service told AFP that IS put up tough resistance Wednesday in the Maamun Flats area of southwest Mosul, which he said is considered "important for the control of the surrounding neighbourhoods".
"The resistance is violent and fierce because they're defending this line and this line, in our opinion, is the main line for them," Staff Lieutenant General Abdulghani al-Assadi said.
- Threat from snipers -
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Iraq's Joint Operations Command announced later Wednesday that CTS had recaptured Maamun Flats.
The damage in the Maamun area is heavy, with homes destroyed, roads cratered and rows of crumpled cars, some of them piled one on top of another.
Fleeing Mosul residents have spoken of dire conditions inside the city.
"We're so hungry, we haven't eaten almost anything in four days," said Widaa, a 20-year-old who fled Maamun.
"There was firing all around our house, it was being destroyed bit by bit," she said.
The drive to retake west Mosul -- the smaller but more densely populated side of a city split by the Tigris River -- began on February 19, after Iraqi troops retook its east side the previous month.
Sniper fire is a significant danger in Maamun, said Kathy Bequary, the executive director of NYC Medics, a group providing emergency care from a mobile clinic.
"We're seeing a lot of serious gunshot wounds from snipers," Bequary told AFP.
"Most of our patients are combatants, but civilians are affected too. Two days ago, we treated a family -- a mother, father, son and daughter -- who were trying to escape Mosul and were targeted by snipers," she said.
"The five-year-old daughter was shot in the pelvis, a through and through wound. The girl was very, very critical."
IS overran large areas north and west of Baghdad in 2014, announcing a "caliphate" incorporating swathes of Iraq and Syria.
While security forces initially performed dismally, they have since retaken most of the territory they lost, with backing from US-led air strikes and other support.
IS has also lost significant ground in Syria, and while it still holds the city of Raqa and some territory in western Iraq in addition to in Mosul, the jihadists' "state" is crumbling.
The operation to retake Mosul was launched on October 17, involving an array of sometimes rival security forces and paramilitary groups.