Isis (Islamic State) has said that it has seized a second gas field in Syria.

The SITE jihadist website monitoring service says that soldiers of the extremist organisation posted pictures showing raised IS flags in a gas field located in the central province of Homs.

It is the second gas field that the terrorist organisation has seized within the last week after it took the Sha'ar gas field towards the end of last week following fights with Syrian forces.

IS militants now occupy a third of Syria and the group has declared a 'caliphate' on what it has conquered.

"So after the [Sha'ar] company and the [positions] surrounding it became part of the land of the Caliphate, the soldiers advanced, conquering new areas, and all praise is due to Allah," IS said in a message obtained by SITE.

"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."

IS also claims to have taken control of a plethora of armoured vehicles which include two tanks and seven four-wheel drive cars, plus "several" heavy machine guns.