Iraqi security forces have advanced further into towns north of Baghdad in a new offensive to retake the country's biggest oil refinery from Islamic State of Iraq and the Levant fighters. Battles have been raging for the past two weeks between government troops and the ISIL group near both the city of Beiji, the command centre for the self-declared jihadists, and the Beiji oil refinery, located about 200 kms from Baghdad. Al Jazeera's Imran Khan reports from Baghdad.