In order to buy cheap oil produced in Islamic State (IS) controlled territories, sources say there are queues of trucks up to 40km long.

A security source from Kirkuk Province told BasNews that IS insurgents have established almost 50 oil fields in Hawija [55 km south west of Kirkuk].

The anonymous source said that a refinery in the area has three refining tanks.

A 40km line of trucks transfer the oil from the Ajil field in the north of Salahaddin Province to the Syrian border where it’s sold, according to the source.

“IS does not only control oil fields in the area and the means to export the oil, they also have mobile refineries inside controlled areas and sell it locally,” said the source.

He explained that the jihadists have manufactured oil tanks similar to water tanks but bigger in size.

The tank is divided into three parts. Once a fire is set underneath the tanks, petroleum floats to the top, white oil sits in the middle and gasoline falls to the bottom.

The 40 km long line of IS trucks is obvious but has not been targeted by international coalition jets, according the the source.

Ajil oil field is one of the biggest in Iraq, located in the north of Salahaddin Province.

The field is made up of 91 wells that produce more than 20,000 barrels per day.

The field also has a production capacity of 1.2m cubic metres of natural gas, and has been under the control of IS since June 2014.

A separate source from the North Oil Company told BasNews, “There are criminals behind the smuggling of Ajil oil with connections to IS militants and some Iraqi political parties.”