PLEASE NOTE: EDIT CONTAINS MATERIAL THAT WAS ORIGINALLY 4:3<br/> <br />ROUGH CUT - NO REPORTER NARRATION<br/> <br />Two bombs concealed in air conditioning units inside a Sunni mosque south of the Iraqi city of Samarra exploded during Friday (September 20) prayers, killing at least 15 people, police and hospital sources said.<br/> <br />It was not immediately clear who was behind the attack, which took place in al-Mafraq, around 10 km (6 miles) south of Samarra.<br/> <br />At least 17 people were wounded, the sources said.<br/> <br />Iraq's delicate sectarian balance has come under growing strain from the civil war in neighbouring Syria, where mainly Sunni rebels are fighting to overthrow a leader backed by Shi'ite Iran.<br/> <br />Both Sunnis and Shi'ites have crossed into Syria from Iraq to fight on opposite sides of the conflict.<br/> <br />Al Qaeda's Syrian and Iraqi branches merged earlier this year to form the Islamic State of Iraq and the Levant, which has claimed responsibility for attacks on both sides of the b
