Alleged Balkan drug lord Sreten Josic goes on trial Monday on charges of being an accomplice in the murder of the owner of the Croatian magazine "National" Ivo Pukanic.

On Sunday the Serbian daily “Press” claims Bulgarian Prime Minister Boyko Borisov could be called on the witness stand during the trial over Josic’s statements that Borisov provided protection for him at the time he was the Bulgarian Interior Ministry Chief Secretary.

Josic was also reported Friday to to have planned the assassination of Serbian Justice Minister Snezana Malovic.

Josic, also known as Joca Amsterdam, was detained at the end of April. Serbian police reportedly expect his arrest to lead to clues related to the murders of a number of mafia bosses, who were important players in cocaine trafficking from Latin America to Europe.

Most of them are believed to be Bulgarian underworld lords, who were Josic's partners in the supply and distribution of cocaine.

Josic has been linked to the assassinations of Poli Pantev, who was killed in March 2001 in Aruba, Konstantin Dimitrov a.k.a. Samokovetsa, shot dead in broad daylight in Amsterdam in December 2003 and Ivan Todorov - Doctora, who found his death in February 2006 in downtown Sofia.

At the beginning of April Sreten Josic made headlines in Bulgaria, telling a Belgrade court he enjoyed the protection of high-ranking officials here, citing the names of the then Interior Chief Secretary Boyko Borisov, who was later elected Sofia mayor and prime minister of the country, and Nikolay Gigov, owner of Lokomotiv football club.

Borisov vehemently denied the allegations, accusing the former ruling three-party coalition of crafting a long-term strategy to discredit him.