Huge stacks of $100 bills have been found hidden behind a false wall by US troops searching a house in Baghdad.
US forces have been checking buildings throughout Baghdad
If genuine, the amount discovered could be as great as $600m, US Brigadier-General Vince Brooks said.
Videotape of the recovery of the cash showed many piles of the banknotes wrapped in plastic stacked inside metal boxes.
There is speculation that the cash had to be left behind by regime leaders fleeing as coalition forces advanced on the Iraqi capital.
The money was found during an anti-looting operation, General Brooks said. It has been taken on a military cargo plane to a safe - and undisclosed - location.
"The money is first to be secured and examined by law enforcement officers to determine if it's real money," he said.
The Los Angeles Times newspaper reported that one soldier who checked the notes said the watermarks appeared genuine and the bills contained the thin metal strip designed to beat counterfeiters.
"Watermarks, metallic strips, the ink doesn't rub off. It's our currency, genuine US cash," it quoted Private David Lauderman as saying.
Night-time treasure hunt
The newspaper said two US army sergeants became curious when they stumbled on a sealed-up cottage in an area where senior Baath Party and Republican Guard officials had lived.
They broke in and found a neat line of metal boxes, each containing a fortune.
That discovery led to a mass night-time search of the area in which more than 100 cases stuffed full of cash were recovered, the newspaper reported.
General Brooks said decisions would be taken later on what to do with the money - once it has been determined if it is genuine - whose it was and what it was for.