"Such stone balls were never found in Europe before, and Bosnia and Herzegovina is the only European country to report such findings.
The stone balls phenomena are also recorded in Costa Rica and Mexico, and now, in Bosnia and Herzegovina."
Source : Press release from the Foundation, 6th september 2006 (bs)
It is not only easy to find numerous examples of stone spheres (see here a collection from almost every continent), but even in Europe Bosnia is not the only country with spheres, as is shown on these pages written by Jiri Matejka in 2003-2004.
Spheres in Czech Republic:
Spheres in Slovakia:
Spheres in Poland: