(CNN) -- "Federal regulators investigating possible price manipulation of crude oil are likely looking at what role collapsed energy giant Enron may have played, a former government official said Friday."

"There is a theory that has gained momentum among economists and market observers that the price of crude oil is being driven up not by supply/demand principles in whole, but by speculators who are using what are called dark markets, markets that can't be watched by the public or regulators, to manipulate the price of crude oil and, therefore, gasoline and heating oil in an upward direction," he said.

"He added, "It would be as if you said you could trade stocks on the New York Stock Exchange but you could also trade stocks somewhere where the Securities [and] Exchange Commission had no idea what was going on, and at the behest of Enron in late 2000 in a lame duck Congress, this kind of unregulated trading was permitted."

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