The performer of the most popular Bulgarian folk song, which was launched into space in 1977, has initiated a probe into its use in a documentary movie for Afghanistan by National Geographic.

"Izlel e Delyo Haidutin", sung most famously by Valya Balkanska, was used in the documentary movie "Restrepo", showing the life of American soldiers in Afghanistan.

The movie director, Sebastian Junger, who is also a famous American author and journalist, has won the grand jury prize for a domestic documentary at the 2010 Sundance Film Festival.

However, in the movie, Junger has decided to use the Bulgarian song as a background to the presentation of the situation in Afghanistan without a permission.

"I still don't understand how this beautiful Bulgarian song ended up as musical background in a movie about the Talibans. I don't know the director Sebastian Junger, he still has not contacted me. I have hired people to check that," Valya Balkanska said in an interview for 24 Hours daily.

"How is it possible that this man managed to find the song, but failed to find me?," wonders the popular folk singer.

She admits that the most frustrating thing for her was to understand that Junger's wife, who told him about the song, is Bulgarian.

However, Junger claims he had the copyrights for using the song, which has been National Geographic's request.