LONDON, April 20 (NNN-KUNA) -- Iraq could hold almost twice as much oil in its reserves as had been thought, according to the most comprehensive independent study of its resources since the US-led invasion in 2003, it was revealed here.

The potential presence of a further 100 billion barrels in the western desert highlights the opportunity for Iraq to be one of the world's biggest oil suppliers, and its attractions for international oil companies, if the conflict in the country can be resolved, the Financial Times newspaper said Thursday.

If confirmed, it would raise Iraq from the world's third largest source of oil reserves with 116 billion barrels to second place, behind Saudi Arabia and overtaking Iran.

The study from the consultancy firm "IHS" also estimates that Iraq's production could be increased from its current rate of less than two million barrels a day to four million barrels a day within five years, if international investment begins to flow.

That would put Iraq in the top five oil-producing countries in the world, at current rates, the main business daily in Europe added.

The IHS study is based on data collected in Iraq both before and after the invasion, showing the oilfields' reserves and production history. Its estimate is based on analysis of geological surveys.

Production costs in Iraq are low, particularly compared to the more complex offshore developments. IHS estimates that they are less than USD 2 a barrel.

But the development of the industry depends on an improvement in the security environment, which remains very difficult.

Ron Mobed of IHS said, "Obviously the security situation is very bad, but when you look at the sub-surface opportunity, there isn't anywhere else like this. Geologically, it's right up there, a gold star opportunity."

Of Iraq's 78 oilfields identified as commercial by the government, only 27 are currently producing.

A further 25 are not yet developed but close to production, and 26 are not yet developed and far from production.

Iraq's government has estimated that it would need USD 20-25 billion of investment from foreign companies to get production up to its full potential.