MOSUL, Iraq - 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.