Warning: some viewers may find this video distressing Terror group Isis releases a video purporting to show a group of unarmed Iraqi soldiers being questioned before one of them is killed by their captors. Iraqi men, some in military uniform, have been brutally questioned, and one seemingly murdered, by apparent al-Qaeda insurgents during their campaign to capture of several large cities in the Gulf country. These two clips show a group at least five men, some in military fatigues, seated on the ground with their hands tied behind their backs. The insurgents question them about their ethnicity, at one point placing the barrel of a rifle in one of the prisoner's throats. In the second video, one of the prisoners is dead with a gunshot wound to the head, while the suspected insurgent waves an identity card in front of a camera, naming the prisoner he killed and proclaiming off camera "God is great. I killed a Shia". The videos were posted on several social media websites by individuals supporting the insurgency in Iraq. The imagery is likely to fuel sensitivity over alleged brutality by the Sunni Islamist insurgents who last week seized control of Iraq's second-largest city of Mosul and have swept south towards Baghdad. The onslaught by militants of the Islamic State of Iraq and the Levant (Isis) threatens to dismember Iraq and unleash all-out sectarian warfare across a crescent of the Middle East. Get the latest headlines http://www.telegraph.co.uk/ Subscribe to The Telegraph http://www.youtube.com/subscription_center?add_user=telegraphtv Like us on Facebook http://www.facebook.com/telegraph.co.uk Follow us on Twitter https://twitter.com/telegraph Follow us on Google+ https://plus.google.com/102891355072777008500/ Telegraph.co.uk and YouTube.com/TelegraphTV are websites of The Daily Telegraph, the UK's best-selling quality daily newspaper providing news and analysis on UK and world events, business, sport, lifestyle and culture.