Shelling and bombings across Iraq killed 28 people Saturday and militants blew up a key bridge linking the capital to the north, the latest in a surge of violence.
The bloodshed, which pushed the death toll for January to more than 800, comes in the run-up to a general election scheduled for April 30, and has stoked fears Iraq is slipping back into all-out conflict.
Faced with a weeks-long standoff in Anbar province, west of Baghdad, and Iraq's worst protracted unrest since 2008, authorities have been urged by foreign leaders to pursue political reconciliation in a bid to undercut support for militants.
But Prime Minister Nuri al-Maliki has taken a hard line with a view to the looming election, and officials have trumpeted security operations.
Shelling began late on Friday in the south Fallujah neighbourhood of Nazal and continued into the early hours of Saturday, killing eight people including a young child, and wounding seven, said Doctor Ahmed Shami of the city's main hospital.
Residents of the city on Baghdad's doorstep blame the army for the shelling. Defence officials insist the military is not responsible.
Near Anbar provincial capital Ramadi farther west, security officials said they killed 20 militants in the Albu Faraj area, state television reported.
Fallujah and parts of Ramadi have been in the hands of anti-government fighters for weeks, some of them from the Al-Qaeda-linked Islamic State of Iraq and the Levant (ISIL).
It is the first time militants have exercised such open control in Iraqi cities since the peak of the violence that followed the 2003 US-led invasion.
Fighting erupted in the Ramadi area on December 30, when security forces cleared a year-old Sunni Arab protest camp.
Violence then spread to Fallujah, as militants moved in and seized the city and parts of Ramadi after security forces withdrew.
The government says it is fighting Al-Qaeda, and Fallujah residents and tribal sheikhs have said ISIL has tightened its grip on the city. But other militant groups and anti-government tribes have also been battling government forces in Anbar.
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140,000 people have fled
The protracted standoff has prompted more than 140,000 people to flee their homes, the UN refugee agency said on Friday, with its spokesman Peter Kessler describing it as the worst displacement in Iraq since the 2006-08 sectarian conflict.
Violence also struck in the capital, and north of Baghdad on Saturday, leaving 20 others dead.
A mortar attack in Jaizan, a Shiite village just north of the confessionally mixed city of Baquba, killed six people and wounded two, security and medical officials said.
Among the dead were two women and a young boy.
Baquba is the capital of Diyala province, which has a Sunni majority but substantial Shiite Arab and Kurdish populations. The province remains one of Iraq's least stable and is the site of frequent violence.
Car bombs in two Sunni-majority neighbourhoods of Baghdad killed three people and wounded more than a dozen, officials said, and a magnetic "sticky bomb" attached to a car killed a provincial government official in the capital.
Two policemen were killed by a roadside bomb in Balad, just north of Baghdad.
Four people were also killed in a flurry of attacks in Mosul, and three bombings in the ethnically mixed town of Tuz Khurmatu left four others dead.
Militants also bombed a bridge north of Baghdad on a key highway to the northern oil city of Kirkuk and the autonomous Kurdistan region beyond, officials said.
The blast completely destroyed a 20-metre (yard) section of the bridge and five people were injured when their car careered off it immediately after the explosion.
The authorities have been grappling with a protracted surge in violence, which is at its highest level since Iraq was emerging from a brutal sectarian war in 2008.
Upwards of 800 people have been killed already this month, more than three times the death toll for January 2013, according to an AFP tally.