A previously unknown piece of music by one of the world's most celebrated composers has been uncovered.

The 12-minute piece by Austrian composer, Wolfgang Amadeus Mozart, is called "Ganz kleine Nachtmusik" and was likely written when he was a teenager sometime in the mid-to late-1760s. Researchers found the manuscript while putting together the latest update to the Köchel Catalog, the official archive of Mozart's music which has existed for more than 160 years. The latest edition of the catalog took more than 10 years to compile and is the first update since 1964, according to the International Mozarteum Foundation, a nonprofit organization focused on the life and works of Mozart by offering free concerts, maintaining Mozart museums and supporting academic research.

The piece written for a string trio is a significant piece in the mosaic of Mozart's music, according to Ulrich Leisinger, head of research at the International Mozarteum Foundation and editor of the latest version of Köchel.

"Until now the young Mozart has been familiar to us chiefly as a composer of keyboard music and of arias and sinfonias but we know from a list drawn up by [his father] Leopold Mozart that he wrote many other chamber works in his youth, all of them unfortunately lost." Leisinger said in a statement.