According to the opposition-aligned MASAR news agency, the militants seized control over Kharta oil field after two days of fierce clashes in the region with the Syrian opposition group, Al-Mujahideen Brigades.
Reports say a fire erupted in an oil pipeline which was hit during the fighting.
The Syrian Revolution General Commission (SRGC) stated that the electricity and water supply had been cut off across the city early Sunday.
The Islamic State of Iraq and Levant is a hardline militant group fighting in the northern and eastern regions of war-torn Syria, in a bid to establish their own state. The group is also present in Iraq, as its name indicates.
Syria has been gripped by constant fighting since the regime launched a violent crackdown in response to anti-government protests in March 2011, triggering a conflict that has spiraled into a civil war.
The UN has stopped updating its death toll for the country because an official count had become too difficult to verify. At least 100,000 deaths were recorded in the last official count in July 2013.
Over two and a half million are registered as refugees in neighboring Turkey, Lebanon and Iraq.
