Toxic oil wells blaze as IS retreats
Media playback is unsupported on your device
Video

IS oil wells set on fire as Iraqi troops approach Mosul

So-called Islamic State has set 19 oil fields ablaze leaving a vast toxic cloud over Mosul and surrounding towns in Iraq.

Iraqi forces entered the city's outskirts for the first time on Tuesday since the city was seized by IS militants in June 2014.

Go to next video: Helping Iraqi children deal with trauma