Shia militia in Iraq have made gains in the south and northwest against fighters from the Islamic State in Iraq and Levant (ISIL).<br /><br />But some have been accused of killing Sunni civilians in revenge attacks, a claim the groups deny.<br /><br />Al Jazeera has been given exclusive access to one of the militias in Salahudeen province - as the group prepares for an assault on the ISIL stronghold of Tikrit. <br /><br />Al Jazeera's Imran Khan reports from Salahudeen province.
