Sunni fighters led by the Islamic State in Iraq and the Levant (ISIL) have expanded their offensive in Iraq, capturing more territory from the government.
ISIL, an al-Qaeda breakaway group active in Syria and Iraq, has taken the towns of Qaim, Rawah and Anah in Anbar province. Qaim, located on the border with Syria, hosts a key crossing between the two countries.
Fighters also claim to be in full control of the northern city of Baiji, which hosts Iraq's biggest oil refinery, though the military denies the rebels control the refinery itself.
The Associated Press news agency, citing Iraqi miltary officials, reported that Sunni fighters captured two border crossings, the Turaibil crossing with Jordan and the al-Walid crossing with Syria, on Sunday.
The vast Anbar province stretches from the western edges of the capital, Baghdad, all the way to Jordan and Syria to the northwest. Fighting in the predominantly Sunni region has disrupted use of the highway linking Baghdad to the Jordanian border, a key artery for goods and passengers.
In January, fighters in Anbar overran the city of Fallujah and parts of Ramadi.
The latest gains by ISIL are a further blow to Nouri al-Maliki, Iraq’s Shia prime minister, whose grasp on his job is coming under increasing pressure as the rebels try to push the country towards a sectarian showdown.
The capture of the town of Rawah on the Euphrates River and the nearby town of Anah appeared to be part of a march towards a key dam in the city of Haditha. Any destruction of the dam would have a serious impact on the country's electrical grid and cause major flooding.
Military officials said more than 2,000 troops were quickly dispatched to the site of the dam to protect it against a possible attack, the AP news agency reported.
Al Jazeera's Imran Khan, reporting from Baghdad, said there is significant ISIL movement in Anbar on Sunday, adding that the province is increasingly coming under the control of fighters.
"After taking over Qaim, Rawah and Anah, armed groups are now advancing to the next town, Haditha in the west of Ramadi city, and are negotiating with tribal leaders to enter there peacefully," he said.
"Army forces have left Haditha and have moved to the town of Khan al-Baghdadi and the military base of Ein al-Asad."
On Saturday, Shia armed groups rallied across the country vowing to protect religious sites and making a very deliberate show of force against ISIL.
The biggest of the rallies, which were called for by powerful religious leader Moqtada al-Sadr, took place in the northern Baghdad suburb of Sadr City, where hundreds of men dressed in combat fatigues and carrying assault rifles marched in military formation. Sadr's Mahdi Army militia is believed to have as many as 100,000 fighters.
Prime minister pressured
Maliki's Shia-led government has struggled to defeat the rebels who have seized large swathes of the country since taking control of the second-largest city of Mosul on June 10 after government forces melted away.
|Map: The Islamic State's (formerly ISIL) path through Iraq
Maliki, who has led the country since 2006, has increasingly turned to Iranian-backed Shia fighters and volunteers to bolster his beleaguered security forces.
His State of Law party won the most seats in an April parliamentary election but a new government has not yet been formed, and rivals have started to challenge him from within the broader Shia alliance.
To stay in power, his bloc, which won 92 seats, must form a majority coalition in the 328-seat legislature, which has to meet by June 30.