CAMP TARIQ, Iraq — Iraqi forces said Thursday that they are continuing to push into the Islamic State-held city of Fallujah, having secured its outskirts.

Iraqi officers said the large number of civilians in the city was slowing down the military operation, because fewer airstrikes could be carried out.

Iraqi forces are heavily dependent on airstrikes to achieve territorial victories against the Islamic State.

The US-led coalition said it had carried out four airstrikes in and around Fallujah since Wednesday.

The strikes hit fighting positions, a weapons cache, and a tunnel system.

Fallujah is one of the last Islamic State strongholds in Iraq.

The militants also hold Mosul, the second largest city.

Associated Press