The fighting for Mosul has been intense over the past week after Iraqi special forces broke through ISIS defence lines to enter the city early in the week.

Since then, troops have been embroiled in brutal, close-quarter combat with waves of suicide bombers and snipers. The elite Iraqi Counter Terrorism Service troops are the spearhead of a wider coalition of 100,000 fighters seeking to crush a few thousand Islamic State in Iraq and Syria (ISIS) militants who have ruled Mosul for the last two years.

The campaign to retake Iraq's second-largest city, which is now almost a month old, is the most complex military operation in Iraq in the 13 years of turmoil since the US invasion. More than 49,000 people have been displaced since the Mosul operation began, the International Organisation for Migration said yesterday. But with weeks, if not months, of fighting ahead, aid workers have warned that the numbers may spike.