An espionage group has been uncovered for the first time, the Prosecutor's Office said after the arrest of 6 Bulgarian military and former intelligence officers, BTA has reported.

The network was organized by a former senior member of the Military Intelligence Service, called the “Resident,” who graduated from an intelligence school in Moscow. He recruited people with access to classified information from Bulgaria, NATO and the EU. The Resident's wife with Bulgarian and Russian citizenship was in contact with the Russian Embassy in Sofia.

The rest held senior government positions. One is a senior member of the Ministry of Defense's planning department. There are two Military Intelligence officers involved, as well as a former military intelligence officer who worked as a secretary, military attache, and defense attache.

The investigation is of particular importance for the security of Bulgaria, the EU, NATO and the United States. There has been no other such case since 1944, Prosecutor General Ivan Geshev said.

"This is not the first time we have witnessed actions by foreign embassies incompatible with the Vienna Convention on Diplomatic Relations, and we define these cases as inadmissible. Bulgaria's Foreign Ministry will continue to act in accordance with established international practice in establishing such cases," the Bulgarian Foreign Ministry said in a statement distributed to the media.