Baghdad, Sep 29: The Islamic State no longer controls any of Iraq's oil wells after government forces drove the jihadist group from the northern town of Shirqat, Iraqi Petrol Ministry's spokesman Asim Jihad said on Wednesday.
IS also recently lost control of the Qayyarah oil in an offensive to liberate Nineveh province, he said.
Only the Najma oil well is not yet back under government control, but is now problematic for IS to operate, according to Jihad.
"Najma has yet to be liberated because some of the area is a war zone. But it's very hard for IS to extract and smuggle oil while are forces are advancing towards Mosul," he said.
US and Iraqi commanders have said the long-awaited ground campaign re-take Mosul from IS could begin by the second half of October.
The largely Sunni city is IS's main bastion Iraq and the 'capital' of its self-styled Caliphate, which extends across swathes of territory in Iraq and Syria.
IS overran Mosul in June 2014 during a lightening sweep across Iraq's north and west.