The Iraqi army has begun an operation to storm Fallujah, the Islamic State group's stronghold, in a final showdown to retake the city.

A military unit is advancing on the city, just 50 kilometers west of capital Baghdad. Supported by Iranian-backed Shi'ite militia, the Iraqi army has now begun a direct assault from three directions.

In January 2014, Fallujah became the first Iraqi city to fall under the control of the militants. Only a few hundred families managed to slip out of the Fallujah area ahead of the assault by the Iraqi forces. An estimated 50 thousand civilians are still trapped inside.