Kurdish forces and Islamic State fighters were clashing in a town only 40 kilometres southwest of the Kurdish regional capital of Erbil in northern Iraq, a senior Kurdish official said on Wednesday.
Jabbar Yawar, secretary-general of the ministry of the Kurdish peshmerga fighters, told the Reuters news agency military cooperation had been re-established with Baghdad in a bid to hit back against the Sunni fighters who staged another dramatic push through the north over the weekend.
Yawar said 50,000 members of Iraq's Yazidi ethnic minority who fled the offensive and are hiding on a mountain near the town of Sinjar risked starving to death if they are not rescued in 24 hours.
The UN Security Council on Tuesday condemned attacks by self-declared jihadists in northern Iraq, saying that those responsible could face trial for crimes against humanity, amid fears the region's Yazidi minority could be wiped out.
Iraqi helicopters dropped supplies to thousands of desperate people hiding in mountains from Islamic State fighters, as officials on Tuesday warned that the Yazidi in the town of Sinjar, near the Syrian border, risked being massacred or starved into extinction in the face of the group's takeover of the region.
A Yazidi politician broke down in tears during a parliament session as she urged the government and the international community to save her community from Islamic State fighters who have overrun the region, AFP news agency reported.
"Over the past 48 hours, 30,000 families have been besieged in the Sinjar mountains, with no water and no food," Vian Dakhil said.
"Seventy children have already died of thirst and 30 elderly people have also died."
Dakhil said 500 Yazidi men had been killed by the fighters since they took over Sinjar and surrounding villages on Sunday. Their women were enslaved as "war booty", she said.
"We are being slaughtered, our entire religion is being wiped off the face of the earth. I am begging you, in the name of humanity."
The Security Council said Islamic State fighters posed a threat not only to Iraq and Syria, but to "regional peace, security and stability".
"Widespread or systematic attacks directed against any civilian populations because of their ethnic background, religion or belief may constitute a crime against humanity, for which those responsible must be held accountable," said a Security Council statement read by Mark Lyall Grant, the British ambassador.
Grant singled out the plight of the Yazidi, a closed community that follows an ancient faith rooted in Zoroastrianism and referred to by the Islamic State as "devil worshippers".
"Many of these Iraqis have been displaced or forced to flee and seek refuge, while many others have been executed and kidnapped," said the Council statement.
Sinjar is also a temporary home for thousands of displaced people from other minorities, such as Shia Turkmen who fled the nearby city of Tal Afar when the jihadists launched their offensive on June 9.
The attack on Sinjar sent thousands of people running from their homes in panic, some of them scurrying into the mountains with no supplies.
"Families who fled the area are in immediate need of urgent assistance, including up to 25,000 children who are now stranded in mountains surrounding Sinjar and are in dire need of humanitarian aid, including drinking water and sanitation services," UNICEF said.