Some 500,000 Iraqis have fled their homes in Iraq's second city Mosul after Jihadist militants took control, fearing increased violence, the International Organization for Migration said Wednesday.
The Geneva-based organization said its sources on the ground estimated the violence leading up to the Islamic State of Iraq's total takeover on Tuesday "displaced over 500,000 people in and around the city".
Fighters belonging to the al-Qaeda-linked Islamic State in Iraq and Syria (ISIS) have advanced into the oil refinery town of Baiji, Reuters quoted security sources as saying on Wednesday, Al Arabiya reported.
The ISIS militants set the town's court house and police station on fire, the sources said.
The refinery is protected by around 250 guards, and security sources said the militants had sent a delegation of local tribal sheikhs to convince them to withdraw.
The guards agreed to pull out on the condition that they were transferred safely to another town, the sources added.
ISIS jihadists seized control of Mosul, Iraq's second-largest city, and the surrounding province of Nineveh on Tuesday.
Witnesses from Bashiqa, a town east of Mosul, told Agence France-Presse by telephone that gunmen stood guard at government buildings and banks, while dozens of families continued to flee the city.
Areas west of Kirkuk have also fallen under the control of ISIS fighters after the Iraqi army withdrew its forces on Tuesday, Al Arabiya's correspondent reported.
They managed to seize Kirkuk's Zab and Abbasi areas, while battles continued at the borders of the Hawijah and Rashad.
Kurdish forces reportedly besieged Kirkuk on Wednesday to prevent ISIS militants from spreading, a military source told Al Arabiya News Channel.
Iraqi Prime Minister Nuri al-Maliki on Tuesday 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."
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.