Iraqi forces Wednesday wrested back control of key areas west of Baghdad that have been out of government hands for weeks amid a deadly standoff between militants and security forces.

The battles in Anbar province, a mostly-Sunni desert region bordering on Syria, and a protracted surge in nationwide violence, have killed more than 850 people this month, fuelling fears Iraq is slipping back into the all-out conflict that plagued it from 2006 to 2008.

Washington has said it plans to sell Iraq 24 Apache attack helicopters in a $4.8 billion deal to help the country fight militants.

But foreign leaders have also urged the Shiite-led government to address long-term grievances in the disaffected Sunni community to undercut support for militancy.

Security forces and allied tribal fighters regained control Wednesday of Albu Farraj, just north of Ramadi, as well as a district on the outskirts of Fallujah, officials said.

"Iraqi security forces have taken control of Albu Farraj," said defence ministry spokesman Mohammed al-Askari, describing the area as an "important base" for militants, including the Al-Qaeda-linked Islamic State of Iraq and the Levant (ISIL).

"We will give it back to the tribes and police forces to return the area to normal."

Officials said Iraqi forces also took back Al-Nasaf, on the western outskirts of Fallujah.

Security forces have been locked in battles in Ramadi, where militants hold several neighbourhoods, and have carried out operations in rural areas of Anbar province.

Anti-government fighters also hold all of Fallujah, on Baghdad's doorstep.

ISIL has been involved in the fighting, and witnesses and tribal leaders in Fallujah say the group has tightened its grip on the city in recent days, but other militant groups have also taken part in the battles.

It is the first time militants have exercised such open control in Iraqi cities since the peak of violence that followed the 2003 US-led invasion.

The standoff has forced more than 140,000 people to flee their homes, the UN refugee agency said, describing this as the worst displacement in Iraq since the 2006-2008n conflict.

In Baghdad and the main northern city of Mosul, multiple shootings and bombings killed seven people Wednesday, including two members of the security forces and three anti-Qaeda militiamen.