Prime Minister Nuri al-Maliki vowed Saturday to eliminate "all terrorist groups" in Iraq's Anbar province, where militants have seized all of one city and parts of another.

"We will not back down until we end all terrorist groups and save our people in Anbar," Maliki was quoted as saying by Iraqiya state television.

Parts of Ramadi and Fallujah, west of Baghdad, have been held by militants for days, harkening back to the years after the 2003 US-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 marginalisation and targeting of their community.

It then spread to Fallujah, and security forces later withdrew from areas of both cities, leaving them open for Al-Qaeda-linked militant group the Islamic State of Iraq and the Levant to move in.

On Saturday, a senior security official in Anbar province said that Fallujah was completely outside government control, and in the hands of ISIL.

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.