An operation to retake Iraq's second city from Islamic State control has begun.

The push in Mosul - led by Kurdish and Iraqi forces - will be the biggest operation in the country since American troops left in 2011.

Thousands of leaflets have been dropped over the besieged city warning civilians of the imminent military offensive.

It's been planned for months, but that time's also allowed the militants to prepare, and it's thought they've booby-trapped entire streets.

And Iraq's prime minister Haider al-Abadi's had a message for them on state TV: