A previously unknown piece of music composed by Wolfgang Amadeus Mozart when he was probably in his early teens has been uncovered at a library in Germany.

The piece dates to the mid to late 1760s and consists of seven miniature movements for a string trio lasting about 12 minutes, the Leipzig municipal libraries said in a statement on Thursday.

Born in 1756, Mozart was a child prodigy and began composing at a very early age under his father’s guidance.

Researchers discovered the work at the city’s music library while compiling the latest edition of the Köchel catalogue, the definitive archive of Mozart’s musical works.

The newly discovered manuscript was not written by Mozart himself but is believed to be a copy made in about 1780, the researchers said.

The piece was performed by a string trio at the unveiling of the new Köchel catalogue in the Austrian city of Salzburg on Thursday.

It will receive its German premiere at the Leipzig Opera on Saturday.

The piece is referred to as Ganz kleine Nachtmusik in the catalogue, according to the Leipzig libraries.

The manuscript consists of dark brown ink on medium-white handmade paper and the parts are individually bound, they said.

The Köchel catalogue describes the piece as “preserved in a single source, in which the attribution of the author suggests that the work was written before Mozart’s first trip to Italy”, according to the municipal libraries.