BAGHDAD: Sunni insurgents led by an Al-Qaeda breakaway group expanded their offensive in a volatile western province Saturday, capturing two strategic towns and the first border crossing with Syria to fall on the Iraqi side.

It's the latest blow against Prime Minister Nouri al-Maliki, who is fighting for his political life even as forces beyond his control are pushing the country toward a sectarian showdown.

In a reflection of the bitter divide, thousands of heavily armed Shiite militiamen - eager to take on the Sunni insurgents - march through Iraqi cities in military-style parades on streets where many of them battled U.S. forces a half decade ago

The towns of Qaim and Rawah are the first territory seized in Anbar province, west of Baghdad, since fighters from the Islamic State of Iraq and Greater Syria (ISIS) group overran the city of Fallujah and parts of the provincial capital of Ramadi earlier this year.

Sunni militants have carved out a large fiefdom along the Iraqi-Syrian border and have long traveled back and forth with ease, but control over crossings like that one in Qaim allows them to more easily move weapons and heavy equipment to different battlefields. Syrian rebels already have seized the facilities on the Syrian side of the border and several other posts in areas under their control.

Police and army officials said Saturday that the Sunni insurgents seized Qaim and its crossing, about 320 kilometers west of Baghdad, after killing some 30 Iraqi troops in daylong clashes Friday.

The officials, who spoke on condition of anonymity because they were not authorized to talk to journalists, said people were now crossing back and forth freely.

Chief military spokesman Lt. Gen. Qassim al-Moussawi acknowledged Qaim's fall, telling journalists that troops aided by local tribesmen sought to clear the city of "terrorists."

Sunni militants also captured the Euphrates River town of Rawah, ransacking government offices and forcing local army and police forces to pull out, Mayor Hussein AIi al-Aujail said. The town, which had remained under government control since nearby Fallujah fell, also lies dangerously close to an important dam near the city of Haditha.

Military officials said more than 2,000 troops were quickly dispatched to the site of the dam to protect it against a possible attack by the militants. They spoke on condition of anonymity because they were not authorized to speak to the media.

The vast Anbar province stretches from the western edges of Baghdad all the way to Jordan and Syria to the northwest. The fighting in Anbar has greatly disrupted use of the highway linking Baghdad to the Jordanian border, a key artery for goods and passengers.

Maliki's Shiite-dominated government has struggled to push back against Islamic extremists and allied Sunni militants who have seized large swaths of the country's north since taking control of the second-largest city of Mosul on June 10 as Iraqi government forces melted away.

The prime minister, who has led the country since 2006 and has not yet secured a third term after recent parliamentary elections, also has increasingly turned to Iranian-backed Shiite militias and Shiite volunteers to bolster his beleaguered security forces.

The parades in Baghdad and other mainly cities in the mainly Shiite south revealed the depth and diversity of the militia's arsenal, from field artillery and missiles to multiple rocket launchers and heavy machine guns, adding a new layer to mounting evidence that Iraq is inching closer to a religious war between Sunnis and Shiites.

Maliki has come under growing pressure to reach out to disaffected Kurds and Sunnis, with many blaming his failure to promote reconciliation led to the country's worst crisis since the U.S. military withdrew its forces nearly three years ago.

In Baghdad, about 20,000 militiamen loyal to anti-U.S. Shiite preacher Muqtada al-Sadr, many in military fatigues and even some wearing red berets, white gloves and combat helmets, marched through the sprawling Shiite Sadr City district, which saw some of the worst fighting between Shiite militias and U.S. soldiers before a cease-fire was reached in 2008 hat helped stem the sectarian bloodshed that was pushing the country to the brink of civil war.

Similar parades took place in the southern cities of Amarah and Basra, both strongholds of Sadr supporters.

Grand Ayatollah Ali al-Sistani, the most respected voice for Iraq's Shiite majority, on Friday joined calls for Maliki to reach out to the Kurdish and Sunni minorities a day after President Barack Obama challenged him to create a leadership representative of all Iraqis.

Sistani normally stays above the political fray, and his comments, delivered through a representative, could ultimately seal Maliki's fate.

Maliki's State of Law bloc won the most seats in the April vote, but his hopes to retain his job have been thrown into doubt, with rivals challenging him from within the broader Shiite alliance. In order to govern, his bloc, which won 92 seats, must first form a majority coalition in the new 328-seat legislature, which must meet by June 30.

If Maliki were to relinquish his post now, according to the constitution, the president, Jalal Talabani, a Kurd, would assume the job until a new prime minister is elected. But the ailing Talabani has been in Germany for treatment since 2012, so his deputy, Khudeir al-Khuzaie, a Shiite, would step in for him.

The U.S., meanwhile, has been drawn back into the conflict with so much at stake. Obama announced Thursday he was deploying up to 300 military advisers to help quell the insurgency. They join some 275 troops in and around Iraq to provide security and support for the U.S. Embassy and other American interests.

Obama has been adamant that U.S. troops would not be returning to combat but has said he could approve "targeted and precise" strikes requested by Baghdad.

Manned and unmanned U.S. aircraft are now flying over Iraq 24 hours a day on intelligence missions, U.S. officials say.

Iraq enjoyed several years of relative calm before violence spiked a year ago after Maliki moved to crush a Sunni protest movement against what the minority sect claimed was discrimination and abuse at the hands of his government and security forces.

Meanwhile, on Saturday four separate explosions killed 10 people, including two policemen, and wounded 22 in Baghdad, according to police and hospital officials. And in an incident harkening back to the peak days of sectarian killings in 2006 and 2007, two bodies, presumably of Sunnis, were found riddled with bullets in Baghdad's Shiite district of Zafaranieh, police and morgue officials said.

All officials spoke on condition of anonymity because they were not authorized to speak to journalists.