Unknown Mozart’s compositions in Poland?

Experts from famous Mazarteum in Salzburg in Austria will probably examine wheather compositions, which were found in musical collection in Jasna Góra, signed by Wolfgang Amadeusz Mozart, are really the famous composer works of art.
On 24th April Polish Press Agency (Polska Agencja Prasowa) informed that in collection in Jasna Góra, unknown Mozart’s compositions may be found. On 2th May, during International Festival of Sacred Music "Gaude Mater" (Międzynarodowego Festiwalu Muzyki Sakralnej) in Częstochowa, one of the composition, an aria, was peformed.
Until now it was unknown piece of work signed by Mozart, music sounded as his artistic works. We hope that this festiwal effects in more detailed study on this composition. If it is true, that this is Mozart’s work, it would be a sensation on worldwide scale – said then festival director Małgorzata Nowak.
As dr hab. Remigiusz Pośpiech from University in Opole, chairman of Scientific and Editorial Team of Music in Jasna Góra (Zespołu Naukowo- Redakcyjnego Jasnogórskich Muzykaliów) informed today, he will be striving for the best, that is Austrian and German experts in Mozart’s artistic works, probably also with Mozarteum in Salzburg, to study this piece of art.
The Team found in collection in Jasna Góra 20 manuscripts singned by Mozart, from which 7 are worldwide known, in 4 other cases it was affirmed that other composers were the authors of these manuscripts, 9 of them are unknown pieces of art, which are not included in master’s artistic works catalogue.
Chances that these are really Mozart’s compositions, until the assertion that somebody else is an author, are like 50 to 50. To determine about his autorship, very detailed analysis of style, phrase after phrase, comparing other works, is needed. We want it to be done by experts with international reputation – said dr Pośpiech.