Iraqi forces backed by a US-led air coalition targeted so-called Islamic State defences on the eastern edge of Mosul with artillery fire and air strikes, a day after fighting for the first time inside the city.
The Iraqi Counter Terrorism Service (CTS) entered the state television station in the city, capturing the first important building since the start of the offensive about two weeks ago.
Blackish grey smoke hung in the air east of the Islamists' stronghold and the regular sound of outgoing artillery fire could be heard, said a Reuters reporter near Bazwaia, about 5km east of Mosul.
Explosions could be heard further east.
Iraqi forces have cleared scores of villages and towns on the Nineveh plain east of the city and are advancing along the Tigris river from the south.
But fighting inside the city itself, the jihadists' last big bastion in Iraq and still home to 1.5 million residents, could take months.
The offensive, involving regular army forces, elite counter terrorism units, federal police, Kurdish peshmerga fighters and Shia militias, is the most complex since the 2003 US-led invasion which toppled Saddam Hussein.
Mosul is many times bigger than any other city controlled by IS in either Iraq or Syria.
Its recapture would mark the end of the Iraqi wing of the caliphate which it declared in parts of both countries two years ago although the hardline Sunni militants have recovered from previous setbacks in Iraq.
Iraqi Prime Minister Haider al-Abadi said yesterday that Iraqi forces were trying to close off all escape routes for the several thousand IS fighters inside Mosul.
"God willing, we will chop off the snake's head," Mr Abadi told state television.
"They have no escape, they either die or surrender."
The United Nations has said the Mosul offensive could trigger a humanitarian crisis and a possible refugee exodus if the civilians inside in Mosul seek to escape, with up to one million people fleeing in a worst-case scenario.
The International Organisation for Migration said that so far nearly 18,000 people had been displaced since the start of the campaign on 17 October, excluding those forced back into Mosul by the retreating jihadists.
