Iraqi forces have moved deeper into the city of Ramadi, parts of which are still under the control of ISIS.

Army officials say bombs and booby traps have been slowing their advance.

Troops and Sunni tribal fighters were about 500m from the main local government office.

The Iraqi forces have taken control of several districts since launching the operation five days ago. The mainly Sunni Arab city, about 90km west of Baghdad, was captured by ISIS in May.

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 said 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.