Al-Qaeda-linked militants took control of the central areas of the city of Fallujah in Iraq, an Al Arabiya correspondent reported on Saturday.
The reports came as a senior security official in the western Anbar province said the Iraqi government had lost control of the city to the militants.
"Fallujah is under the control of ISIL," the official said, referring to al-Qaeda-linked group the Islamic State of Iraq and the Levant. 
The al-Qaeda fighters have seized military equipment provided by the U.S. Marines to Fallujah police, whose headquarters have been taken over, Uthman Mohamed, a local reporter in the city in Iraq’s western Anbar province, told Bloomberg news agency.
On Saturday, there was no sign of government forces inside Fallujah, and most of the fighting took place on a highway that links the city to Baghdad, Bloomberg reported.
Parts of Ramadi and Fallujah, west of Baghdad, have been held by militants for days, harkening back to the years after the 2003 U.S.-led invasion when both cities were insurgent strongholds. 
Fighting erupted in the Ramadi area Monday, when security forces removed the main anti-government protest camp set up after demonstrations broke out in late 2012 against what Sunni Arabs say is the marginalization and targeting of their community.
It then spread to Fallujah, and security forces later withdrew from areas of both cities, leaving them open for ISIL to move in.
Fighting between police and allied tribesmen on one side and ISIL militants on the other killed more than 100 people in Ramadi and Fallujah on Friday, security officials said.
It was the deadliest single day for Iraq in years.