A government airstrike killed 25 al-Qaeda-linked militants in a besieged province west of Baghdad amid fierce clashes Tuesday between Iraqi special forces and insurgents battling for control of the key cities of Fallujah and Ramadi, Iraqi officials said.

The al-Qaeda gains in the Sunni-­dominated province of Anbar — once a bloody battleground for U.S. troops — pose the most serious challenge to Prime Minister Nouri al-Maliki’s Shiite-led government since the departure of American forces from Iraq in late 2011.

Iraqi forces and fighters from government-allied Sunni tribes have been battling militants to try to recapture the strategic territory, seized last week by an al-Qaeda-linked group known as the Islamic State of Iraq and Syria.

Gen. Mohammed al-Askari, a spokesman for the Iraqi military, cited intelligence reports as he said that the Iraqi air force struck an operations center for the militants on the outskirts of Ramadi, the provincial capital, killing 25 fighters holed up inside. It was not possible to independently verify the assertion.

The airstrike came after clashes erupted about 12 miles west of Fallujah following the capture of an army officer and four soldiers in the area a day earlier, provincial spokesman Dhari al-Rishawi said. There was no word on casualties.

Maliki’s government has vowed to rout the militants, calling on Fallujah residents Monday to expel the al-Qaeda fighters to avoid an all-out battle.

Iraq’s cabinet met Tuesday to discuss the situation in Anbar and called for the mobilization of all efforts “to support the army and security services in expelling terrorists,” according to a government statement.

Military operations would continue, the statement added, until Iraq is “cleansed” of terrorism.

Witnesses said residents have been streaming out of Fallujah, about 35 miles west of Baghdad, fearing an impending assault.

A medical official in Fallujah said two civilians were killed and five were wounded, including two children, when they were caught Tuesday in an exchange of fire between militants and Iraqi troops south of the city.

The immediate trigger for the unrest was the Dec. 28 arrest of a Sunni lawmaker sought on terrorism charges, followed by the government’s dismantling of a months-old sit-in in Ramadi by Sunnis protesting the government.

Sectarian tensions in Iraq have been rising for much longer as the Sunnis, a minority in the country, increasingly accused the government of discrimination and random arrests on terrorism charges. A U.S.-backed revolt by Sunni tribal leaders against al-Qaeda led to a decline in the sectarian violence that followed the 2003 U.S.-led invasion, which ousted Saddam Hussein, and the current unrest has raised fears that the country is again being pushed to the brink of civil war.

Violence spiked after the government staged a deadly crackdown on a Sunni protest camp in April. Militants also have targeted civilians, particularly in Shiite areas of Baghdad, with waves of coordinated car bombings and other deadly attacks.

The attacks continued Tuesday when a suicide bomber rammed his explosives-laden truck into a police station in the northern city of Kirkuk, killing two people, officials said.

A roadside bomb struck an army patrol southeast of Baghdad, in the Madain area, killing a soldier, and another bomb hit a patrol of pro-government Sunni militiamen in the southeastern Baghdad suburb of Jisr Diyala, killing one, police said.

— Associated Press