Iraqi government forces attempted to encircle Mosul's Old City on Thursday in a bid to bottle up Islamic State fighters holding out there, but progress was slowed by car bombs and booby-traps in houses and alleyways, officers said.
The army and security forces have made significant gains in recent days in the battle that started back in October, seizing a main bridge over the Tigris river and advancing towards the mosque in the Old City from where Islamic State's leader declared a caliphate in 2014.
But the fighting is expected to become even harder as the militants defend their last enclaves in what was once their stronghold in Iraq.
"We have a plan to surround the Old City. Today we have advanced from the right and left sides and the only part left is right in the middle. God willing we will continue this plan today," Federal Police Major General Haidar Dhirgham said.
The need to ensure the safety of civilians, many of them hungry from a lack of provisions and traumatized by living under Islamic State's harsh rule, was also a priority.
"I expect the liberation of Mosul completely in one month. I will not tell you one or two weeks, because that's not true, but within one or two months it will be completely liberated," Dhirgham told Reuters.
Several more areas of western Mosul had been recaptured, including the hospital, over Wednesday and Thursday morning.
"There are only some neighbourhoods that remain, like the Old City. This is too narrow but our forces will be able to enter soon."
As many as 6,000 IS fighters remained in Mosul, including other Arab nationalities and foreigners, he said.
Suicide bombers were driving explosive-rigged cars at troops. There had been three such attacks on Thursday morning, he said. Troops has also seized buildings in which suicide vehicles were being prepared.
"The enemy...has started to set fire to houses which means that are on the retreat. They have destroyed homes and have destroyed families," Dhirgham said.
Mosul has served as Islamic State's de facto capital since its leader Abu Bakr al-Baghdadi proclaimed himself head of a caliphate spanning Iraq and Syria from the Nuri Mosque in July 2014.
The recapture of the city by the government would drive the remnants of the IS army into the hinterlands. In neighbouring Syria, three separate forces are advancing on the city of Raqqa, the main Syrian city under Islamic State control.
As well as waging jihad in Iraq and Syria, the militants have inspired attacks in cities in Europe, Africa and elsewhere that have killed hundreds of civilians.
U.S. and other Western countries have been providing air, artillery and other support to the Mosul offensive, reflecting the international concern over the IS threat.
However, the presence of tens of thousands of civilians in IS-held areas means that simply pulverising them is a risky proposition. Thousands of residents have escaped to government lines in recent days but it has been impossible to tally the number of civilian casualties.
"We will liberate civilians before liberating the land," Dhirgham said. "We will take them out of the neighbourhoods, if we have their consent. If they would like to flee to an area in the back flanks or if we could secure them within their neighbourhoods, we will secure them in their homes."