The Islamic State (IS) has taken 80 percent control of Iraq's largest oil refinery in Baiji while country's forces have lost significant ground in the last few days, a senior U.S. official said.
According to the CNN, the militants have successfully advanced to several refinery areas in recent days, and are keeping the Iraqi forces from being re-supplied.
The official said that the Iraqis forces, which include Army, national police and counterterrorism units at the site, would have to find a way to regain the possession of the besieged refinery if they lose it.
The official added that U.S. and coalition fighter jets are not striking inside refinery in view of keeping as much of the infrastructure as protected for the future.
The besieged refinery, which has been non-operational for sometime, is also considered strategic due to being located on a major approach route to the city of Mosul, which Iraq forces hope to retrieve from ISIS in the coming months.