The Iraqi security forces  launched a major offensive in the western province of Anbar to free a town from where the Islamic State (IS) militants abducted around 43 people and later burned them alive inside iron cages, a provincial security source said.

Iraqi soldiers, police and allied Sunni tribesmen, backed by the US-led coalition and Iraqi aircraft, advanced in the morning from three directions to free the town of al-Baghdadi, some 200 km northwest of the Iraqi capital, Xinhua news agency reported citing the source.

The offensive was also designed to break the siege of a neighbourhood adjacent to al-Baghdadi, where some 1,000 families of security members and government-backed Sahwa paramilitary group members have been trapped, the source said.

The troops managed to let humanitarian aid reach the families suffering from acute shortage of food and drinking water for about 10 days.

The troops surrounded the town while heavy clashes broke out around the area and in some neighbourhoods of al-Baghdadi town.

“The streets clashes which broke out today (Saturday) will continue until the troops clear the town from the last extremist militant,” the source added.

Earlier, a security source said the IS militants burned up to 43 people alive in the nearby town of Heet, after abducting them from the militants-seized town of al-Baghdadi. The kidnapped people were believed to be local police and Sahwa fighters.

The executions came after the killing of some 70 others in the past 10 days when the IS militants carried out major attacks on al-Baghdadi and the nearby air base of Ain al-Asad which is housing hundreds of US Marines.

However, their attacks on the air base were repelled by security forces and US aircraft, while fighting continued in and around the town.

The Ain al-Asad military base is used by Iraqi military forces, as well as roughly 300 US Marines as military trainers and advisers.

The IS group has seized around 80 percent of Iraq’s largest province of Anbar and has been trying to advance toward Baghdad, but several counter attacks by security forces and Shia militias have pushed them back from western areas of the capital.

Since December last year, there have been insurgent attacks in the Sunni Arab heartland west of Baghdad which stretches through the Anbar province.

Anbar province was the scene of fierce clashes which flared up after police disbanded an anti-government protest outside Ramadi city.

The security situation in Iraq started drastically deteriorating since June 10 last year, when bloody clashes broke out between Iraqi security forces and IS — an Al Qaeda offshoot.

IS took control of the country’s northern province of Nineveh, and later seized swathes of territory after Iraqi security forces abandoned their posts in other predominantly Sunni provinces.