bust of Mozart
© Sean Gallup/Getty ImagesA bust of Austrian composer Wolfgang Amadeus Mozart stands in the garden of Bertramka Villa, taken on January 22, 2006, in Prague, Czech Republic
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.

Leipzig Municipal Libraries revealed the good news in a statement and that the piece will have its debut on Saturday at the Leipzig Opera.

The piece of music was a copy or a transcription of the original music, so likely not handwritten by Mozart himself and found in the Music Library of the Leipzig Municipal Libraries.

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.

"It looks as if - thanks to a series of favourable circumstances - a complete string trio has survived in Leipzig. The source was evidently Mozart's sister, and so it is tempting to think that she preserved the work as a memento of her brother.

Leisinger said, "Perhaps he wrote the Trio specially for her and for her name day."

Mozart's newly discovered piece consists of seven miniature movements for a string trio, and the manuscript was produced with dark brown ink on medium white laid paper and the parts are bound separately and the manuscript is unsigned, per the Leipzig Libraries.

Newsweek contacted the Leipzig Municipal Libraries via an online contact form for comment.

Mozart was born in 1756 in Salzburg, Austria, and was quickly identified as a child musical prodigy. He began showing a remarkable talent at the keyboard and even writing his own compositions at a young age.

Even though he died at the relatively young age of 35, Mozart managed to compose more than 800 musical works and is "widely regarded as one of the greatest composers in European music history," according to American musicologist David J Buch.