US-backed Iraqi forces have launched a new push toward the Islamic State-held old city centre of Mosul.

Iraqi forces are fighting their way toward the old centre of the city, advancing from the south and the southwest, Brigadier-General Yahya Rasool, spokesman for the joint operations command, told state-run television today.

Iraqi forces captured the eastern side of Mosul in January after 100 days of fighting and launched their attack on the districts that lie west of the Tigris river on February 19.

Their advance in western Mosul paused over the past 48 hours because of bad weather.

Defeating Islamic State in Mosul would crush the Iraqi wing of the caliphate declared by the group's leader, Abu Bakr al-Baghdadi, in 2014, over parts of Iraq and Syria.