WASHINGTON - September 13, 2010 - Economists peddling dire warnings that the world's number one economy is on the brink of collapse, amid high rates of unemployment and a spiraling public deficit, are flourishing here.

The guru of this doomsday line of thinking may be economist Nouriel Roubini, thrust into the forefront after predicting the chaos wrought by the subprime mortgage crisis and the collapse of the housing bubble.

"The U.S. has run out of bullets," Roubini told an economic forum in Italy earlier this month.

But other economists, who have so far stayed out of the media limelight, are also proselytizing nightmarish visions of the future.

Boston University professor Laurence Kotlikoff, who warned as far back as the 1980s of the dangers of a public deficit, lent credence to such dark predictions in an International Monetary Fund publication last week.

He unveiled a doomsday scenario - which many dismiss as pure fantasy - of an economic clash between superpowers the United States and China, which holds more than 843 billion dollars of U.S. Treasury bonds.

"A minor trade dispute between the United States and China could make some people think that other people are going to sell U.S. Treasury Bonds," he wrote in the IMF's Finance & Development review.

"That belief, coupled with major concern about inflation, could lead to a sell-off of government bonds that causes the public to withdraw their bank deposits and buy durable goods."

Kotlikoff warned such a move would spark a run on banks and money market funds as well as insurance companies as policyholders cash in their surrender values.

"In a short period of time, the Federal Reserve would have to print trillions of dollars to cover its explicit and implicit guarantees. All that new money could produce strong inflation, perhaps hyperinflation," he said.

"There are other less apocalyptic, perhaps more plausible, but still quite unpleasant, scenarios that could result from multiple equilibria."