The largest dam in Iraq is at risk of an imminent collapse that could unleash a 20 million wave of water on Mosul, a city of 1.7 million people, the US has warned.

In May, the US told Iraqi authorities to make Mosul Dam a national priority, as a catastrophic failure would result in a 'significant loss of life'.

However, a $27 million (£13 million) US-funded reconstruction project to help shore up the dam has made little or no progress.

Iraq says it is reducing the risk and insists there is no cause for alarm.