Shiite fighters paraded in Baghdad Saturday in a dramatic show of force aimed at Sunni militants who seized a Syrian border crossing, widening a western front in an offensive threatening to rip Iraq apart.
Meanwhile, Washington readied a new diplomatic bid to unite Iraq's fractious leaders and repel insurgents whose lightning offensive has displaced hundreds of thousands, alarmed the world and put Prime Minister Nuri al-Maliki under growing pressure.
And in a sign the broad alliance of jihadists and anti-government elements behind the assault may be fracturing, internecine clashes killed 17 fighters in northern Iraq.
Security forces announced they were holding their own in several areas north of Baghdad, but officials said insurgents led by the Islamic State of Iraq and the Levant (ISIL) jihadist group seized one of three official border crossings with Syria.
The takeover came a day after 34 members of the security forces were killed in the border town, giving the fighters greater cross-border mobility into conflict-hit Syria.
The seizure of Al-Qaim leaves just one of three official border crossings with Syria in the hands of the central government. The third is controlled by Kurdish forces.
Anti-government fighters already hold parts of the western province of Anbar, which abuts the Syrian border, after taking all of one city and parts of another earlier in the year.
It is unclear what impact the latest move will have on the overall offensive, as militants already have free rein along most of the 600-kilometre (375-mile) border, neither side of which is controlled by government forces.
- Internecine clashes -
ISIL aims to create an Islamic state that will incorporate both Iraq and Syria, where the group has become a major force in the rebellion against President Bashar al-Assad.
Seventeen fighters were killed in Friday clashes between ISIL and the Army of the Men of the Naqshbandiyah Order (JRTN), another Sunni insurgent group, in militant-held territory in northern Kirkuk province.
The Sunni insurgents driving the offensive are made up of a broad alliance of other groups, such as loyalists of now-executed dictator Saddam Hussein.
Analysts say it is unclear if the alliance can survive given its disparate ideologies.
The battle for the strategic northern town of Tal Afar was in its seventh day, Maliki's security spokesman said Saturday, with government forces holding some neighbourhoods.
Northeast of Baghdad, shelling targeting militant-held villages near the town of Muqdadiyah killed six civilians, police and a doctor said.
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In Baghdad, thousands of armed fighters loyal to powerful Shiite cleric Moqtada al-Sadr paraded in the Sadr City district, vowing to fight the offensive which began on June 9.
Rank upon rank of fighters, wearing mostly camouflage but with some in black, carried Kalashnikov assault rifles, shotguns, sniper rifles, light machineguns and rocket launchers.
Some carried Iraqi flags, while others held signs with messages including "We sacrifice for you, O Iraq," "No, no to terrorism," and "No, no to America".
Fighters interviewed by AFP stressed they were not against any specific religious sect, and that their aim was to defend Iraq.
- Kerry's diplomatic push -
Similar parades were held in large southern cities in the Shiite heartland.
The parades and clashes came as US President Barack Obama dispatched Secretary of State John Kerry to Europe and the Middle East in a new push for unity among Iraq's fractious political leadership.
While Kerry is expected to travel to Iraq, it is not known when he will do so.
Obama's refusal so far to agree to Iraq's appeal for air strikes on the ISIL-led militants has prompted Baghdad's powerful Shiite neighbour Iran to claim Washington lacks the will to fight terror.
Washington says Iran has sent a "small number" of operatives into Iraq.
Obama told CNN on Friday: "There's no amount of American fire power that's going to be able to hold the country together."
The president has insisted that Washington is not slipping back into the morass, but has offered up to 300 advisers and left open the possibility of "targeted and precise military action".
Washington already has an aircraft carrier in the Gulf and is flying manned and unmanned surveillance flights over Iraq, while senior US officials say special forces being sent to advise Iraq could call in air strikes if necessary.
The US's push for broader leadership came after Grand Ayatollah Ali al-Sistani, a revered cleric among Iraq's Shiite Muslim majority, called on people to band together against the insurgents before it was too late.
UN aid agencies said they were rushing supplies to Iraq to help more than one million people displaced by the latest violence and unrest earlier this year.
Turkey, meanwhile, said it will provide fuel to Iraq's Kurdistan region to make up for a shortage caused by the militant offensive that has closed Iraq's biggest oil refinery at Baiji.