Iraqi security forces clash with Sunni militants near Kirkuk, to the north.

The Islamist rebels have taken control of cities and towns north of Baghdad.

Oil-rich Kirkuk was also at stake.

But amid the sweeping advance of rebels, government forces abandoned their posts on Thursday and Kirkuk fell into the hands of Kurds.

They run an autonomous region here and consider Kirkuk their historical capital.

In just a matter of days, Sunni rebels called ISIL, they're an off shoot of al Qaeda, have effectively seized control of Iraq's main population centers in the north.

This amateur video, which Reuters can't independently verify, purports to show an ISIL rebel fighter addressing a crowd of supporters.

The rebels want to set up a strict Sunni caliphate on both sides of the Iraq-Syria frontier.

These are the men the government hopes can push the rebels back.

Hundreds of volunteers have been arriving at army recruitment centers in Basra to jo