Iraq rebels fired mortars at Baghdad's main oil refinery late Friday in a renewed assault on key infrastructure as a US commander suggested such attacks marked a new twist in insurgent tactics. A huge fire broke out at the Dura oil refinery on the outskirts of the capital after it was hit by two mortar rounds, oil ministry spokesman Assem Jihad said. Some 150 firefighters battled the blaze for more than two hours before putting it out. Three people suffered minor burns, Jihad said. "It appears to be a mortar that hit one of the pipelines attached to one of the resevoirs," Oil Minister Ibrahim Bahr al-Ulum, who visited the plant after the attack, told AFP. "It is all under control now -- the reservoir is damaged a bit but the refinery will be operating at capacity again."