US soldiers at a base near the northern Iraqi city of Mosul have donned protective masks against toxic fumes from a sulphur plant set afire in fighting with Islamic State.<br/><br/>They took the precaution after wind blew smoke from the fire towards Qayyarah air field. US Defence Secretary Ash Carter is in Baghdad on an unscheduled visit.<br/><br/>Meanwhile, advancing Iraqi forces entered the town of Qaraqosh, south of Mosul. Qaraqosh, Iraq's largest Christian town before the war, is said to be largely empty but IS has laid landmines on the approaches to Mosul. <br/><br/>The militants have been attacking with suicide bombers elsewhere, driving vehicles laden with explosives at high speed towards government lines. <br/><br/>According to medical sources, IS attack on the city of Kirkuk yesterday, south-east of Mosul, left at least 46 people dead and 120 wounded.