BAGHDAD, July 2 -- Up to 72 people were killed on Thursday in clashes and air strikes by U.S.-led coalition and Iraqi aircraft targeting Islamic State (IS) militants in the provinces of Salahudin and Anbar, security sources said.

In Salahudin province, a suicide car bomber struck the security forces in al-Fatha area in north of the town of Baiji, some 200 km north of the Iraqi capital of Baghdad, leaving seven soldiers and allied militiamen and wounding ten others, a provincial security source told Xinhua on condition of anonymity.

Meanwhile, sporadic clashes continued between the IS militants and the security forces backed by militias known as Hashd Shaabi, or popular mobilization, in the northeastern and northwestern parts of the town of Baiji as the extremist militants are still fighting in some pockets of resistance, the source said.

The security forces and allied militias, covered by Iraqi and international aircraft, cleared on Tuesday most of the town after days of heavy clashes with the extremist militants.

The battles in Baiji came as heavy clashes continue in the nearby Iraq's largest oil refinery as the security forces are fighting to drive IS militants out of the refinery, which the militants are seizing large parts of it.

Also in the province, army helicopter gunships pounded IS positions in Laiyn area in west of the city of Samarra, some 120 km north of Baghdad, leaving at least 17 IS militants killed and destroying a vehicle carrying heavy machine gun, the source said.

Since March 2, security forces and thousands of allied Shiite and Sunni militias have been involved in Iraq's biggest offensive in order to recapture from IS militants the northern part of Salahudin province.

In the western province of Anbar, Iraqi forces and allied militias repelled an attack by dozens of IS militants on military bases outside the IS-held town of Garma, some 40 km west of Baghdad, leaving 25 militants killed and 20 others wounded, along with destroying two vehicles carrying heavy machine guns, a provincial security source anonymously told Xinhua.

The battle near Garma also left two soldiers killed and three others injured, the source said.

Separately, the security forces and allied militias cleared Hitawiyn area in south of the IS-held city of Fallujah, some 50 km west of Baghdad, from the IS militants after one day of an offensive against the IS positions in the area, the source said, adding that the offensive will continue to free nearby areas.

In addition, a fierce clash broke out in the morning when the IS militants attacked an army position in Zoubaa area in southeast of the militant-seized city of Fallujah, some 50 km west of Baghdad, leaving six soldiers killed and destroying two military vehicles, the source said without giving further details about the casualties among the attackers.

Another attack for the IS militants on army position killed 11 soldiers and destroyed three military vehicles in Albu Souda area near the town of Garma, the source said.

Also in the province, artillery bombardment on Albu Hatem area in west of Fallujah killed four civilians and wounded five others, he added.

The IS group has seized most of Anbar province and tried to advance toward Baghdad during the past few months, but several counter attacks by security forces and Shiite militias have pushed them back.

The security situation in Iraq has drastically deteriorated since June 10, 2014, when bloody clashes broke out between Iraqi security forces and IS militants.