The recent air strikes by the United States-led coalition have reportedly targeted four mobile refineries held by the Islamic State of Iraq and Syria (ISIS) and a command centre in Syria.
Early indications suggested that the fresh wave of attacks by the US, Saudi Arabia and United Arab Emirates planes on Sunday were successful, US Central Command said, reported the BBC.
However, no air strikes targeted ISIS positions in the area where Syrian Kurd fighters have been holding out against the militants.
An initial wave of coalition air strikes on Thursday had targeted 12 refineries controlled by the group.
Pentagon had earlier said that small-scale mobile refineries used by the ISIS in Syria generate up to two million dollars a day for the militants.
The U.S.-led coalition of about 40 countries, including Arab states, has vowed to degrade and destroy the ISIS which has captured large swathes of territory in Iraq and Syria.
