Mozart left more than 600 pieces of music before his death at 35
Two piano pieces have been identified as the work of Wolfgang Amadeus Mozart, experts in the Austrian city of Salzburg say.
The compositions have long been in the possession of the International Mozarteum Foundation in the city, the organisation said.
Few details are being released until an official presentation in a week's time.
In January, a piece by Mozart which had lain undiscovered in a French library for years, had its first performance.
A spokeswoman for the Mozarteum Foundation said full details of the most recently identified works would only be made public on 2 August.
She said the music would be performed on Mozart's original fortepiano.
Mozart left more than 600 known pieces of music before his death in 1791 at the age of 35.
He had begun composing at the age of five and his works include operas, chamber music, choral pieces and piano concertos.
The two-minute-long piece performed in public in January for the first time was played by violinist Daniel Cuiller before a small audience in Nantes, western France.
The sheet music had been found by staff at the city's library, and authenticated as the work of Mozart in September 2008.