U.S. government bonds found in the false bottom of a suitcase carried by two Japanese travelers attempting to cross into Switzerland are fake, a U.S. Treasury spokesman said.

"They're clearly fakes," Stephen Meyerhardt, a spokesman for the U.S. Bureau of the Public Debt in Washington, said Wednesday. "That's beyond the fact that the face value is far beyond what's out there."

Italy's financial police said last week they asked the U.S. Securities and Exchange Commission to authenticate the seized bonds, with a face value of more than $134 billion. Rodolfo Mecarelli of the Guardia di Finanza in Como, Italy, said the securities, seized in Chiasso, Italy, were probably forgeries.

Meyerhardt said Treasury records show an estimated $105.4 billion in bearer bonds have yet to be surrendered. Most matured more than five years ago, he said. The Treasury stopped issuing bearer bonds in 1982, Meyerhardt said.

Had the notes been genuine, the pair would have been the U.S. government's fourth-biggest creditor, ahead of the U.K. with $128 billion of U.S. debt and just behind Russia, which is owed $138 billion.

According to the Italian authorities, the seized notes included 249 securities with a face value of $500 million each and 10 additional bonds with a value of more than $1 billion.