The Prime Minister of Iraq has announced the launch of a military assault aimed at taking western Mosul from the Islamic State of Iraq and the Levant (ISIL) group.
Iraqi police and interior ministry forces were expected to start the new phase in their offensive to take control of the entire city by moving on Mosul airport, located on the southern edge of the city, to the west of the Tigris river.
"We announce the start of a new phase in the operation. We are coming to Nineveh to liberate the western side of Mosul," Haider al-Abadi said on television.
Mosul is ISIL's last major urban territory in Iraq.
"Our forces are beginning the liberation of the citizens from the terror of Daesh [ISIL]."
Al Jazeera's Osama Bin Javaid, reporting from Erbil in northern Iraq on Sunday, said several groups were involved in a complex assault on ISIL positions.
"[Mosul is] flanked from the eastern side by counterterrorism forces, from the south by the Iraqi police, and from the north by the Iraqi military and the popular mobilisation forces, also known as the Shia militias," he stated.
As stated by him, about 750,000 civilians are still believed to be trapped in the city's west.
Aid organizations had feared an exodus of unprecedented proportions before the start of the fighting, which began four months ago with a government push on the east, but a significant majority of residents stayed home.
Residents of the west bank have reported difficult living conditions and warned that they were already low on food, with weeks or months of fighting expected to lie ahead.
The Iraqi air force had on Saturday dropped leaflets on the west of the city, warning that a ground attack to push ISIL fighters out was imminent.
"Get ready to welcome the sons of your armed forces and to cooperate with them, as your brothers on the left side have done, in order to reduce losses and speed up the conclusion [of the battle]," read one leaflet.
Other leaflets warned ISIL fighters to "lay down their weapons and surrender".
The defence ministry announced last month that ISIL, also known as ISIS, had been almost completely pushed out of the eastern side of Mosul, which is divided by the Tigris.
It later retracted that statement and fighting continues in some parts of the east.
More than 46,000 people who fled Mosul as fighting raged have, though, been able to return to its eastern districts over the past few weeks despite the pockets of fighting.
Though the west bank of Mosul is slightly smaller than the east, the battle there is expected to be more difficult for government forces, especially in the narrow streets of the Old City.
"West Mosul had the potential certainly of being more difficult, with house-to-house fighting on a larger and more bloody scale," Patrick Skinner, from the Soufan Group intelligence consultancy, told AFP news agency.
The streets around the historic centre, which includes the mosque in which ISIL leader Abu Bakr al-Baghdadi made his only public appearance in June 2014, will be impassable for many military vehicles and force government fighters to take on ISIL in perilous dismounted warfare.
The major push to recapture Mosul was launched on October 17, supported by bombing raids from a US-led coalition.