ERBIL, Iraq (Reuters) - Iraqi troops advanced against Islamic State south of Mosul on Sunday as the U.S.-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 moved toward the village of Haj Ali in tanks and armored vehicles under cover of coalition air strikes and artillery fire, capturing another village on the way.

“In the beginning they resisted but when they saw the force they withdrew,” said an Iraqi officer speaking from the newly recaptured village of Kharaib Jabr, adjacent to Haj Ali.

Haj Ali sits on the eastern bank of the Tigris river, opposite the Islamic State hub of Qayara, where there is an airfield that is set to serve as a staging ground for future operations to recapture Mosul, about 60 km (40 miles) north.

Islamic State overran Mosul two years ago and went on to proclaim a caliphate straddling Iraq and Syria but has come under increasing pressure in recent months, losing ground to an array of forces.

Iraqi forces are also advancing on the edge of the Islamic State bastion of Falluja further south, while in Syria U.S.-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 made modest gains, capturing 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, Iraq deployed an armored division along with boats and bridges to cross the river to Qayara, control of which would also isolate Mosul from territory the militants control further south and east.