Islamic State (ISIL) fighters have set fire to oil wells east of Tikrit in an attempt to hinder aerial attacks, a military source told Reuters.
The oil fields, which produced 25,000 barrels and 4.24 million cubic meters of natural gas per day when ISIL took over the facilities were damaged by bombing in August,
Iraqi troops and Iran-backed Shiite militias are currently advancing on ISIL-held Tikrit as part of a coordinated assault.
