Iraqi Special Forces, which have formed the vanguard of US-backed efforts to retake the Islamic State stronghold of Mosul, have begun a reinvigorated advance into eastern Mosul.

The Associated Press reported the fresh offensive was supported by artillery bombardments and air strikes, sending smoke billowing across the city. Mortars fired from Islamic State (Isis) held areas of the city wounded at least five children as they fled the fighting.

Iraqi forces have successfully liberated swathes of eastern Mosul, establishing a foothold in Iraq's second city. They have begun moving northward into the city's Tahrir district which has been largely left abandoned by its civilian population.

The first troops from the US-backed operation on Mosul entered the limits of the Iraqi city last in early November – after two weeks of advancing through settlements, small towns and villages in the surrounding area.

Roughly 25,000 Iraqi troops, militiamen and Kurdish fighters are involved in the offensive to take back Mosul from the estimated 3,000 to 5,000 IS fighters believed to be inside

As has become their calling card throughout the region, IS has deployed suicide bombers, car bombs and improvised explosive devices to counter US-backed forces.

Inside the areas in the east of the city, where the worst of the fighting has taken place, IS has taken to hiding its fighters in houses and apartment buildings where civilians are still living.

At the outset of the military action on Mosul the UN's human rights agency expressed concerns IS could use the civilian population as human shields.