Al-Qaeda-linked militants tightened their grip on Fallujah, a city on Baghdad's doorstep that has been outside of government control for weeks, as bombings in the capital killed 18 people Monday.
The latest setbacks come as security forces pressed a massive assault on anti-government fighters in Ramadi, another predominantly Sunni Arab city where swathes of territory have been outside of the authorities' control, while a top official warned that militants had enough weaponry to "occupy Baghdad".
Diplomats have urged Iraq to pursue political reconciliation in order to undercut support for militants, but Prime Minister Nuri al-Maliki and others have taken a hard line and trumpeted security operations.
After days of tense calm in Fallujah, a former insurgent bastion a short drive from Baghdad, tribal chiefs and witnesses said Al-Qaeda-linked militants were increasingly exerting their authority in the city on Monday.
Fighters affiliated with the Islamic State of Iraq and the Levant (ISIL) had set up an Islamic court, kidnapped senior officials including a senior police officer and several tribal sheikhs, and broadcast calls over mosque loudspeakers for others to join them in the fight against Iraqi security forces.
"Daash does not accept anything that we decide," said one tribal sheikh, who spoke on condition of anonymity for fear of being targeted by militants, referring to ISIL by its commonly-used Arabic acronym.
"They want everybody to work under their command, under their regime."
Another resident of the city, who gave his name as Abu Osama, said militants had imposed strict codes in some neighbourhoods, including barring women from visiting local markets and men from wearing Western clothes or shaving their beards.
"We do not want to see these gunmen in Fallujah, we do not feel safe with them," Abu Osama told AFP by telephone. "We want the police to come back."
Security forces continued to mount major operations against militants in Ramadi, and in rural areas between the two cities, but the clashes and unrest caused several casualties.
A bombing near Ramadi targeting a group of policemen and media going to ceremonially reopen a police station on Monday killed three people -- two policemen and a journalist -- and wounded three others, including another reporter.
Clashes in Ramadi between security forces and anti-government fighters, meanwhile, left two people dead and 15 others wounded on Sunday evening, while two bombs on Monday north of the city badly damaged two army fuel trucks.
Security forces, meanwhile, said at least seven militants, including a senior ISIL commander, had died in the unrest over the two days.
Heavy clashes and shelling continued into Monday in Ramadi, after soldiers, policemen and allied tribal fighters mounted a major operation to retake militant-held areas of the city a day earlier.
Ramadi and Fallujah were both former insurgent bastions and have been home to months of anti-government protests. Fighters have moved in and taken control of parts of Ramadi and all of Fallujah after recent unrest.
It marks the first time anti-government fighters have exercised such open control since the height of the insurgency that followed the US-led invasion of 2003.
Deputy Interior Minister Adnan al-Assadi warned in a speech on Monday that militant groups fighting in Anbar had amassed "numerous and modern" weapons.
"They are enough to occupy Baghdad," he said. "Their target is not just controlling Fallujah or (the nearby town of) Garma, it is to topple the entire political process."
Deadly violence also struck the capital on Monday, with at least six car bombs ripping through Shiite-majority neighbourhoods, killing 18 people in all, according to security and medical officials.
Baghdad security spokesman Saad Maan, however, said only two people were killed.
No group immediately claimed responsibility for the attack, but Sunni militants including those linked to Al-Qaeda frequently set off coordinated bombings across the capital.
On Saturday evening, a wave of explosions across Baghdad killed 25 people, while 37 more died in a similar spate of attacks on Wednesday.
The attacks were the latest in a protracted surge in nationwide violence that has left more than 650 people dead so far this month, sparking fears Iraq is slipping back into the all-out conflict that plagued it in 2006 and 2007.
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