The defeat would be the biggest yet for the Islamic State group three years since it seized Mosul in a lightning offensive, swept across much of the country's Sunni Arab heartland and proclaimed a "caliphate" straddling Iraq and Syria.
"We are seeing now the last metres and then final victory will be announced", a presenter said, citing correspondents embedded with security forces fighting in ISIL's redoubt in the Old City by the Tigris.
During those seven months, he said he witnessed a "measurable escalation" in ISIS's use of human shields as Iraqi troops pushed further into the city.
As Iraqi troops closed in on Mosul over the past few months, the Islamic State seized civilian homes and trapped families inside while they staged attacks from the rooftops against US -led coalition forces to lure American airstrikes.
Iraqi authorities will imminently announce a final victory, a USA general said on Saturday.
Joint Command had announced that Prime Minister Haider al-Abadi, who is also the commander-in-chief of the armed forces, will be the one to declare final victory.
Anderson said the coalition has begun delivering aid to help Iraqi police increase their presence in Mosul and hold the city after it is liberated.
ISIS leader Abu Bakr al-Baghdadi declared himself "caliph" at the mosque in his only public appearance in 2014.
Commander of the 1st Brigade, Lieutenant Colonel Flalah Al-Wardani said: "Heroes of the Emergency Rapid Division today captured the terrorists' last stronghold in the Old City".
Dozens of ISIL militants were killed on Saturday and others tried to escape by swimming across the Tigris, state television said.
The jihadists wanted to go back, but security forces "fired on them and killed them", he said, without specifying how many died.