"Serbia and Montenegro is by no means trying to avoid determining the responsibility of its citizens for alleged war crimes, so there is no reason for Bulgaria to enter into this legal case because it may have a negative impact on our relations, which have never been better," Tadic said in the letter.
The letter says that Brankovic "undoubtedly enjoys legal immunity from criminal prosecution" under the 1969 Convention on Special Missions, which was ratified by both countries, and that only indictments issued by the Hague war crimes tribunal can have precedence over the convention.
"The public in Serbia and Montenegro is particularly disturbed by pictures of Colonel Brankovic with his hands and feet tied with chains, which is frustrating for both citizens and state officials in Belgrade," the letter said.
Brankovic, who was arrested last Tuesday, was meanwhile released on the basis of diplomatic immunity and was transferred to the Serbia and Montenegro Embassy in Sofia until completion of the diplomatic activities in connection with his case, the Serbia and Montenegro Defence Ministry has told the Belgrade-based Beta news agency.
The county court in the Croatian town of Sisak has launched an investigation into Brankovic on suspicion of involvement in war crimes committed by Serb forces in 1991 in the Novska area, about 100 kilometres east of Zagreb.