Fighters belonging to the al-Qaeda-linked Islamic State in Iraq and Syria (ISIS) seized several areas of the Iraqi province of Kirkuk on Tuesday, Al Arabiya reported.
The militants took control of the Zab and Abbasi areas west of Kirkuk after the Iraqi army withdrew its forces, the reporter said.
Meanwhile, battles continue at the borders of the Hawijah and Rashad areas.
Earlier on Tuesday, jihadists from the same group seized control of Mosul, Iraq's second-largest city, and the surrounding province of Nineveh.
Nineveh, long a militant stronghold and one of the most dangerous areas in Iraq, shares a border with part of western Kirkuk province, which is located north of Baghdad.
Iraqi Prime Minister Nuri al-Maliki offered weapons and equipment to citizens who volunteer to fight Islamist militants.
In a statement broadcast on state television, Maliki said the cabinet has "created a special crisis cell to follow up on the process of volunteering and equipping and arming."
The cabinet "praises the willingness of the citizens and the sons of the tribes to volunteer and carry weapons ... to defend the homeland and defeat terrorism," he said.
Maliki said the cabinet also decided to "restructure and reorganize" the security forces, and to ask parliament to "announce a state of emergency."
Violence is running at its highest levels since 2006-2007, when tens of thousands were killed in clashes between Iraq's Shiite majority and Sunni Arab minority.
The level of violence in Iraq surged last year after an April 23 operation by security forces at an anti-government protest camp near Hawijah that sparked clashes in which dozens died, and has continued unabated since.
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