Tens of thousands of people have fled one of the districts seized by the ISIL fighters in the offensive and are now surrounded, the United Nations said on Monday. The militants often execute people in areas they have captured.
Kurdish peshmerga fighters, who gained experience fighting Saddam Hussein's troops, were regarded as one of the few forces capable of standing up to the insurgents, who faced almost no opposition from Maliki's US-trained army during their lightning advance through the north in June.
Then on Sunday the ISIL inflicted a humiliating defeat on the Kurds with a rapid advance through three towns to reach the Mosul Dam, acquiring a fifth oil field to fund its operations along the way, Reuters reported.
State television and witnesses said the ISIL had seized Iraq's biggest dam. Kurdish peshmerga officials said they had pushed militants from the dam area and were in control of it. This could not be immediately confirmed.
Despite predictions from Kurdish commanders that their forces would launch a successful counter-offensive, one senior Kurdish official urged the United States to step in and provide weapons "for the sake of fighting terrorism".
Kurdish commanders whose units came under attack from the ISIL fighters told Reuters they faced overwhelming firepower, were taken by surprise, and that militants had in many cases started shooting from villages where they had formed alliances with residents.
The areas that the Kurds lost were not part of their semi-autonomous region, but had been seized in the north after the fall of Saddam Hussein.