An armoured vehicle of Libyan forces allied with the U.N.-backed government is pictured during a battle with Islamic State militants in neighbourhood Number Three in Sirte, Libya October 9, 2016. REUTERS/Ismail Zitouny ************************************************************* TRIPOLI (Reuters) – Libyan pro-government forces are advancing into the last area controlled by Islamic State in the coastal city of Sirte, surrounding the militants after a five-month campaign backed by U.S. air strikes, military officials say.At least eight pro-government fighters were killed over the weekend as their forces pushed into the 600 block, an area in central Sirte, with snipers and boobytraps posing the main obstacles...