Bill Gates, whose net worth of $46.6 billion makes him the world's richest person, is betting against the US dollar.

"I'm short the dollar," Gates, chairman of Microsoft, said in an interview at the World Economic Forum in Davos, Switzerland. "The ol' dollar, it's gonna go down."

According to a report on the website of Bloomberg, Gates's concern that the widening US budget and trade deficits are undermining the dollar was echoed in Davos by policymakers including European Central Bank president Jean-Claude Trichet and German Chancellor Gerhard Schroeder.

The trade deficit swelled to a record $609.3 billion last year, and the total US government debt rose 8.7% to $7.62 trillion in the past 12 months.

"It is a bit scary," Gates said. "We're in uncharted territory when the world's reserve currency has so much outstanding debt."

Gates reflected the views of his friend Warren Buffett, the billionaire investor who has bet against the dollar since 2002. Buffett said last week that the US trade gap will probably further weaken the currency.

Gates described China as a potential "change agent" for the next two decades. "It's phenomenal," Gates said. "It's a brand new form of capitalism."