The recent scandal involving leaked phone conversations of high Bulgarian officials has started with an information leak from the State National Security Agency (DANS), according to Interior Minister Tsvetan Tsvetanov.

On Monday, Tsvetanov stated that a DANS employee has failed a polygraph test designed to figure out whether he has anything to do with the recent leaks of classified information. Even though the polygraph cannot be used as official evidence, the Interior Minister was convinced that the whole recent wiretapping scandal has been triggered just from the National Security Agency.

Last Thursday, Tsvetlin Yovchev, former head of the agency, became the first victim of the eavesdropping scandal involving top officials, as PM Boyko Borisov accepted the resignation he submitted "due to the government's consistent lack of trust in his skills".

Before Yovchev resigned on Wednesday, Boyko Borisov said he would execute changes in DANS without hesitating if its leadership fails to provide security of information and to stop the scandalous leaks of classified information

Bulgaria's eavesdropping scandal erupted last month when the controversial Galeria weekly published transcripts of taped phone conversations between senior government officials and Customs Agency head Vanyo Tanov, which prompted Borisov to seek and win a confidence vote in Parliament on January 20.

The recordings of the conversations were made with special surveillance devices, experts from the Bulgarian Academy of Sciences concluded. Special surveillance devices can be used by DANS or the Interior Ministry.