Ulrich Leisinger, who heads up the foundation's research department, said the musical works recently attributed to the classical composer, who died in 1791, had previously been thought to be the work of Mozart's father Leopold, The New York Times reported Sunday.
The incomplete works were found on the back of a music book once used by Mozart's sister Maria Anna. They include 35 measures of a piano prelude and 75 measures of a solo section of a complete movement of a keyboard concerto, Leisinger said.
The suspected Mozart works, which have yet to be fully authenticated, would likely have been created by the famed composer when he was only 7 or 8 years old.
The foundation publicly announced its findings Sunday, but the site has had the music book in its possession since 1864.
Mozart expert Neal Zaslaw, who did not take part in the discovery of the pieces, told the Times it was very plausible the works were, indeed, created by Mozart. Still, Zaslaw added it was unlikely the foundation's claim could be verified with certainty.