ISIS fighters in Syria said on Monday they had taken control of a gas field in the central province of Homs, the second gas field seized in a week after battles with Assad's forces.

The group posted 18 photos on social media showing the ISIS flag raised in the Jahar gas field as well as seized vehicles and weaponry, according to SITE Intelligence Group.

ISIS fighters, who now hold up to a third of Syria as well as swathes of Iraq and have declared a 'Caliphate' on the territories they control, took the larger Sha'ar gas field on Oct. 30.

"Yesterday they tightened control over Jahar village and the Mahr gas pumping company, and nearly nine (positions) supported by heavy weaponry such as tanks, armoured vehicles, and heavy machine guns of various calibres," ISIS said in the message.

The report said ISIS had seized two tanks, seven four-wheel drive cars and several heavy machine guns.

A U.S.-led coalition has conducted air strikes against ISIS since September. The United States says it is not coordinating with Syrian President Bashar al-Assad's forces to combat the ISIS group.