Washington: Oil smuggling, human trafficking, theft and extortion are some of the source of income of the the dreaded terrorist group the Islamic State or the ISIS, according to reports.
As per US intelligence officials and private experts, quoted by a news agency, the ISIS have become a self-sustaining financial force and are said to be earning more than USD three million a day from the above sources.
At one point of time the group relied on wealthy Persian Gulf donors for money.
Is is also being said that that ISIS' resources exceed that of any other terrorist group in history. They are reported to be controlling as many as 11 oil fields in Iraq and Syria.
The per the news agency, an expert said that the price the ISIS fetches for its smuggled oil is discounted USD 25 to USD 60 for a barrel of oil that normally sells for more than USD 100 but its total profits from oil are exceeding USD 3 million a day.
Some of the earlier reports have said that the group now controls a territory which is the size of United Kingdom.
The ISIS expanded during the civil war in Syria. It swept into Iraq in June this year, seizing large areas of the country's Sunni-dominated northern and western provinces.
One of the main reasons for its rise in Syria and Iraq is said to be internal conflict in those countries and weak governments there.
As per a western daily, before ISIS took over the important city of Mosul, their net worth was $875 million (£515 million). Later they added another $1.5 billion to their assets by robbing banks and selling looted military supplies.
As of now, their total worth is reportedly well over £2 billion.
Another source of income for the Islamic State is the trading of antiquities. Some of the antiques are said to be up to 8,000 years old.
In the recent times the US has upped the ante against the terror group with air strikes by its war planes. The air strikes began in early August after ISIS fighters began targeting ethnic Yazidis and launching attacks toward the Kurdish regional capital of Irbil.
Th Iraqi and Kurdish forces have also launched offensive against the ISIS in a major way.
US president Barack Obama vowed to destroy the ISIS after it beheaded a second American citizen and put up the video on the internet.
American journalist Steven Sotloff was killed by the group after the execution of another journalist James Foley.
Meanwhile, a British aid worker was also beheaded by the ISIS on Sunday.
A new two-minute-27-second video titled "A Message to the Allies of America" blames Cameron for joining forces with the US, which has said it is at "war" with the jihadists and launched air strikes against them in Iraq.
Reacting to the news UK PM David Cameron said that it was as an act of "pure evil" even as Britain confirmed that the video showing the gruesome killing was genuine.
The 44-year-old aid worker David Haines was seized in Syria in 2013.
The latest video showing his killing also includes a threat to kill a second British hostage. Cameron vowed to do everything possible to find the killers.
With Agency inputs