MOSUL, Iraq - Iraqi forces are using siege and stealth tactics to drive Islamic State militants out of Mosul's Old City, a Iraqi general said, as his forces sought to minimize casualties among hundreds of thousands of people trapped in the cramped, historic neighborhood.Explosions from two car bombs could be heard nearby as Lieutenant General Abdul Ghani Assadi spoke to Reuters at his command post on Monday, and a Reuters correspondent saw thick smoke rising from the blasts."Most houses in the Old City are very old and its streets and alleyways are very narrow," Assadi, a commander of Iraqi counter-terrorism units in Mosul, said. "So to avoid civilian losses we are using siege, but that does not mean we will not enter the Old City."Assadi said his units were refraining from engaging enemy forces in positions where the militants were holding civilians as human shields."Using very careful methods and considerations, we will liberate our people from Daesh," he added, referring to an Arab acronym of Islamic State. Government forces have surrounded the militants in the northwestern quarter including the Old City, home to the Grand al-Nuri mosque where their leader, Abu Bakr al-Baghdadi, declared a "caliphate" over parts of Iraq and Syria.The ultra-hardline Sunni Muslim fighters are countering the offensive using booby traps, suicide motorcycle attacks, sniper and mortar fire, occasionally shells filled with toxic gas.With food and water supplies becoming scarcer in neighborhoods of Mosul still under IS control, up to half a million people are believed to be trapped there, including 400,000 in the Old City alone, according to United Nations estimate.Lise Grande, the UN Humanitarian Coordinator for Iraq, told Reuters last week fighting in the Old City could lead to "a humanitarian catastrophe, perhaps the worst" in the three-year war to evict Islamic State from Iraq.International aid organizations have estimated the civilian and military death toll at several thousand since the US-backed offensive by government forces to retake Mosul began in October. More than 330,000 people have been displaced so far, according to the International Organization for Migration.Mosul, the largest city in northern Iraq, was captured by Islamic State in mid-2014, but government forces have retaken most of it, including the half that lies east of the Tigris River.Assadi said the battle should end "very soon, God willing" but declined to indicate a time frame. "This is a guerrilla war not a conventional one so we cannot estimate how long it will take; Daesh is fighting house to house."The Iraqi military estimate the number of Islamic State fighters who remain in Mosul at 200 to 300, mostly foreigners, compared with about 6,000 when the offensive started.The militants "don't let themselves get captured," said Assadi. "They came to die and the majority of them are now in hell."