Islamic State conflict: Iraqi forces push deeper into Ramadi
Iraqi forces have moved deeper into Ramadi, pressing an offensive to drive Islamic State militants from the city.
Bombs and booby traps have been slowing their advance, army officials say.
Troops and Sunni tribal fighters were about 500m (550 yards) from the main local government office.
They have taken control of several districts since launching the operation five days ago. The mainly Sunni Arab city, about 55 miles (90km) west of Baghdad, was captured by IS in May.
Its fall was seen as an embarrassing defeat for the army.
Iraqi officials say troops have managed to enter Haouz area - one of the most important IS strongholds in the centre of Ramadi that includes the main offices of the Anbar province administration and the police directorate.
Joint operations command spokesman Brig Yahya Rasool told Reuters news agency US-led coalition air strikes "helped detonate explosive devices and booby-trapped houses, facilitating our advance".
A police captain, Ahmed al-Dulaimi, spoke of "fierce battles" that had killed many IS militants.
At the launch of the operation on Tuesday, the Iraqi army said it expected up to 300 militants inside the city centre to be dislodged within days.
But there is concern for the civilians they have reportedly taken prisoner.
Sources in Ramadi said on Tuesday that the jihadists had carried out raids and mass arrests in an attempt to prevent an uprising in support of the government offensive by the thousands of people living in districts under their control.
The operation to recapture Ramadi, which began in early November, has made slow progress, mainly because the government has chosen not to use the powerful Shia-dominated paramilitary force that helped it regain the northern city of Tikrit to avoid increasing sectarian tensions.
IS has lost control of several key towns in Iraq to government and Kurdish forces since over-running large swathes of the country's west and north in June 2014 and proclaiming the creation of a "caliphate" that also extended into neighbouring Syria.
See where IS have made territorial gains and losses, Jan-Dec 2015
What is Islamic State?
A notoriously violent Islamist group which controls large parts of Syria and Iraq. It has declared its territory a caliphate - a state governed in accordance with Islamic law - under its leader Abu Bakr al-Baghdadi.
What does it want?
IS demands allegiance from all Muslims, rejects national borders and seeks to expand its territory. It adheres to its own extreme interpretation of Sunni Islam and regards non-believers as deserving of death.
How strong is IS?
IS projects a powerful image, partly through propaganda and sheer brutality, and is the world's richest insurgent group. It has about 30,000 fighters but is facing daily bombing by a US-led multinational coalition which has vowed to destroy it.