WASHINGTON (Dow Jones)–A cache of what appeared to be around $135 billion of U.S. bonds seized at the Italian-Swiss border is, in fact, worthless, a Treasury Department spokesman said.

Two alleged Japanese citizens were stopped by Italian authorities June 4 trying to cross into Switzerland with the supposed bonds, hidden in the false bottom of a suitcase, the authorities said.

Authorities said they found 249 certificates worth $500 million each and 10 bonds worth more than $1 billion each, as well as other alleged original banking statements.

Stephen Meyerhardt, a spokesman for Treasury’s Bureau of Public Debt, said Thursday the paper is phony.

“Based on the photos we’ve seen on the Web, they’re not even close to looking like a Treasury security,” he said.

In the 1980s, the U.S. began converting its marketable debt from paper; these days, Treasury securities are issued electronically.

An official at Japan’s Consulate General in Milan said Tuesday that Italy was still investigating the case, adding it wasn’t confirmed the two men are Japanese.

“We sent a letter asking for further information to the Italian tax police as well as prosecutors,” the Japanese official said.

-By Jeff Bater, Dow Jones Newswires; 202 862 9249; [email protected]