United Nations - The United Nations on Thursday apologized after a Serbian group performed a song notoriously linked with the 1995 Srebrenica massacre to UN Secretary General Ban Ki-moon.

“We sincerely regret that people were offended by this song which was not listed in the official program,” UN spokesman Martin Nesirky said in reaction to protests over the singing of “March to the Drina” in a concert at the UN General Assembly on Monday.

Unaware of the song's nationalist connotations, Ban and other top UN officials gave the the Viva Vox choir a standing ovation after they performed “March to the Drina” as their encore at the concert.

“March to the Drina” was originally written in praise of Serbian troops killed during a World War I battle, but has become a nationalist anthem for Serbs.

The words include phrases such as “blood was streaming by the Drina... for Freedom.” “March to the Drina” was reportedly sung by Serb forces during the 1995 massacre in the Bosnian city of Srebrenica in which more than 8,000 Muslim men and boys were slaughtered.

The Drina is Bosnia's longest river and passes through Srebrenica, which was officially under UN protection at the time of the massacre, now considered one of the darkest chapters in UN peacekeeping history.

“We are aware that some people were offended by the encore song at the concert held in the General Assembly on Monday,” Nesirky told reporters.

“The secretary general was obviously not aware what the song was about or the use that has been made of it in the past,” he added.

Vox Viva are an acapella choir from Serbia. Their concert at the UN headquarters was organized by Vuk Jeremic, the former Serbian foreign minister and current president of the UN General Assembly. - Sapa-AFP