Iraqi troops attacked Islamic State positions south of Mosul on Sunday as the US-led coalition intensifies its campaign against the militants on multiple fronts across their self-proclaimed caliphate.

Officers involved in the operation said Iraqi forces had advanced in tanks and armored vehicles toward the village of Haj Ali, about 60 km (40 miles) south of Mosul, under cover of coalition air strikes and artillery fire.

Iraqi forces are also advancing on the edge of the Islamic State bastion of Falluja further south, while in Syria US-backed forces are encircling the militant-held town of Manbij.

Iraqi troops were deployed to the northern Makhmour area earlier this year and launched an operation in March touting it as the beginning of a bigger campaign to retake Mosul - the largest city under militant control.

Since then, Iraqi forces have captured a handful of villages on the eastern bank of the river Tigris.

The commander of the operation blamed the slow pace on a lack of tanks and said he did not have enough men to hold ground after it was retaken from the militants.

Last week, an armored brigade was deployed to Makhmour, along with boats and bridges to enable troops to cross the Tigris river to the Islamic State hub of Qayara on its western bank.

Qayara is home to an airfield that will serve as a key staging ground for the future operation to recapture Mosul, and control of the oil town would also isolate territory the militants control further south and east.