BARTELLA, Iraq — Iraqi forces fought their way into two villages near Mosul today as the offensive to retake the extremist-held city entered its second week and a rights group urged a probe into a suspected airstrike that hit a mosque, killing more than a dozen civilians.

Iraqi special forces began shelling IS positions before dawn near Bartella, a historically Christian town to the east of Mosul that they had retaken last week. With patriotic music blaring from loudspeakers on their Humvees, they then pushed into the village of Tob Zawa, about 5 ½ miles from Mosul, amid heavy clashes.

The Iraqi Federal Police, a military-style force, pushed into a small village in the Shura district south of Mosul, where they fired a large anti-aircraft gun and rocket-propelled grenades as they battled IS militants. They later appeared to have secured the village, a cluster of squat homes on a desert plain, and handed out water and other aid to civilians.

The U.S.-led coalition said it had carried out six airstrikes near Mosul on Sunday, destroying 19 fighting positions and 17 vehicles, as well as rocket and mortar launchers, artillery and tunnels.

Human Rights Watch meanwhile called for an investigation into last week’s purported airstrike in northern Iraq that struck the women’s section of a Shiite mosque in the town of Daquq.

The strike happened amid a large Islamic State assault on the nearby city of Kirkuk that was meant to distract the Iraqi forces and their allies from the massive operation around Mosul, the country’s second largest city.

The IS attack on Kirkuk, 100 miles southeast of Mosul, lasted two days and killed at least 80, mainly members of the Kurdish security forces, who assumed control of the city in 2014 as Iraqi forces crumbled before an IS advance.

Human Rights Watch said Daquq’s residents believe Friday’s attack was an airstrike because of the extent of the destruction and because planes could be heard flying overhead. The New York-based watchdog said at least 13 people were reported killed.

The U.S.-led coalition and the Iraqi military, which are waging the offensive to drive IS from Mosul, are the only parties known to be flying military aircraft over Iraq.

Col. John Dorrian, a U.S. military spokesman, said the coalition had “definitively determined” that it did not conduct the airstrike that killed civilians in Daquq, and had shared its findings with the Iraqi government, which is carrying out its own investigation.

“The Coalition uses precision munitions and an exhaustive process to reduce the possibility of civilian casualties and collateral damage because the preservation of civilian life is (of) paramount importance to us,” Dorrian said.