Saboteurs have set a complex of oil pipelines ablaze in northern Iraq but exports on the line had already been halted by a separate attack at the weekend.
Officials say that a large explosion ripped through the Baiji complex on Monday night.
The complex includes the main pipeline to the northern export terminal at Turkey's Ceyhan port and domestic links from refineries in the oil city of Kirkuk to a nearby power plant.
An official from the North Oil Company says that the blaze could take a couple of days to extinguish.
Saboteurs blew up a section of the northern export pipeline, which can carry 500,000 barrels per day, for the second week in a row on Saturday, halting oil flows to Turkey.
Another domestic oil pipeline was hit near Baiji on the same day.
A wave of attacks has crippled refineries and caused severe fuel shortages and electricity outages, especially in Baghdad.
Sabotage against Iraq's northern oil facilities has been intense since US forces attacked the Sunni city of Fallujah, near Baghdad, last month."
