Iraqi Kurdish forces say they have taken full control of the northern oil city of Kirkuk as the army flees before an Islamist offensive nearby.
"The whole of Kirkuk has fallen into the hands of peshmerga," Kurdish spokesman Jabbar Yawar told Reuters. "No Iraq army remains in Kirkuk now."
Kurdish fighters are seen as a bulwark against Sunni Muslim insurgents who seized towns in the region this week.
The fall of the city of Mosul sent shock waves across the Middle East.
Led by the Islamic State in Iraq and the Levant (ISIS), the insurgents are believed to be planning to push further south, to the capital Baghdad and regions dominated by Iraq's Shia Muslim majority, whom they regard as "infidels".
But it appears the insurgents want to avoid tangling with Iraqi Kurds in provinces bordering Nineveh province where Mosul is located, because they are a more cohesive fighting force, the BBC's Jim Muir reports from Kurdish-run Irbil.
A new insurgent offensive could come from the west, where they control the city of Falluja, 69km (43 miles) from Baghdad, our correspondent adds.
Iraq's parliament is due to debate a call by Prime Minister Nouri Maliki for a state of emergency.
ISIS in Iraq
The Islamic State in Iraq and the Levant (ISIS) has 3,000 to 5,000 fighters, and grew out of an al-Qaeda-linked organisation in Iraq
ISIS has exploited the standoff between the Iraqi government and the minority Sunni Arab community, which complains that Shia PM Nouri Maliki is monopolising power
It has already taken over Ramadi and Falluja, but taking over Mosul is a far greater feat than anything the movement has achieved so far, and will send shockwaves throughout the region
The organisation is led by Abu Bakr al-Baghdadi - an obscure figure regarded as a battlefield commander and tactician. He was once the leader of al-Qaeda in Iraq, one of the groups that later became ISIS.
Kurdish Brig Gen Shirko Rauf told AFP news agency: "We tightened our control of Kirkuk city and are awaiting orders to move toward the areas that are controlled by [ISIS]."
Iraq's Kurds have long sought to incorporate Kirkuk into their autonomous region in the north.
Parts of Kirkuk province were overrun by the Sunni Islamists this week, and some of the civilians fleeing Mosul and other towns have sought refuge in the Kurdish provinces. Others streamed south along with retreating security forces to Baghdad.
The Iraqi prime minister is believed to be asking parliament to grant him powers to impose curfews, restrict public movements and censor the media.
Correspondents say he is unlikely to muster the necessary two-thirds majority in the sharply divided parliament.
Government forces slowed the insurgents' advance on Wednesday outside Samarra, a city just 110km (68 miles) north of Baghdad.
However, according to AFP news agency's sources, the militants have since pushed even further south, bypassing Samarra and seizing the town of Dhuluiya, 90km north-west of Baghdad.
The insurgents also control a large swathe of territory in eastern Syria in a campaign to set up a Sunni militant enclave straddling the border.