Dnevnik published its revelations after having obtained access to restricted information from the Bulgarian prosecution and from the country's eight biggest district courts, under a Bulgarian law on access to public information.
The daily also notes that accessing the information was made possible after months of civic protests and a long fight by human rights groups.
At least 10,000 private communications have been listened to by the authorities in the first seven months since the entry into force of a new law on electronic communications, adopted by the present government, the daily also reveals.
Economists told Dnevnik that Bulgaria spends on eavesdropping 50 times more than the United Kingdom.
A lax formulation of the procedure for requesting a person's communications to be intercepted allows eavesdropping to take place without judicial control, Dnevnik writes.
In particular, an internal directive issued by the country's prosecutor-general Boris Velchev allows prosecutors to request eavesdropping without the authorisation of a judge in cases where a criminal investigation has been opened.
Under this procedure, 2,767 such cases of illegal eavesdropping have already taken place in seven months, Dnevnik reveals.
The Bulgarian press reports a substantial increase of eavesdropping under the government of Boyko Borissov. The previous government of Socialist leader Sergei Stanishev told EurActiv in an exclusive interview that under Borissov, the country was heading towards a 'Polizeistaat'.
For his part, Borissov considers eavesdropping as an important instrument in the fight against organised crime. In an interview for EurActiv, he said he was "at war with the mafia Octopus".
EU information request
A few days ago, the European Commission requested information from the Bulgarian authorities regarding the legality of eavesdropping in the EU newcomer. The request came against a backdrop of a leaked wiretap scandal in which Prime Minister Boyko Borissov was personally involved.
In one of those tapes, Borissov is heard speaking of the need to "protect" a controversial businessman from customs checks.
The wiretaps were apparently made by DANS, the country's national security agency, but were then leaked to Galeria, a tabloid with connections to Alexei Petrov, a controversial figure described by many as Borissov's most powerful enemy.
Borissov promptly asked for a confidence vote in parliament, which he won yesterday (20 January) by 140 votes to 60. All MPs from his party GERB and from Ataka, a xenophobic, nationalist and homophobic party (see 'Background'), voted in favour. The opposition Socialists and the Movement for Rights and Freedoms (MRF), a party harbouring the country's Turkish minority, voted against. The 'Blue Coalition', which brings together leaders from two former anti-Communist parties, abstained.
Eavesdropping scandal could hurt relations with EU
But the vote has not put an end to the eavesdropping scandal. Next month, the European Commission is expected to present a report on progress made by Bulgaria under the Cooperation and Verification Mechanism (CVM), a monitoring procedure put in place with the country's accession in 2007.
Bulgaria and Romania are the only EU members under scrutiny with such a mechanism, as a result of deficiencies in their law enforcement systems, and in the case of Bulgaria, persisting organisd crime.
An EU diplomat who asked not to be named told EurActiv yesterday that by asking for information regarding the legality of eavesdropping in Bulgaria, the Commission was telling Sofia: "We are watching."