Russia says it is expelling two Bulgarian diplomats, nearly three weeks after two staff at the Russian Embassy in Sofia accused of military espionage were told to leave.
Describing Bulgaria's move last month as groundless, Russia's Foreign Ministry said it had summoned Bulgaria's ambassador to Moscow, Atanas Krystin, on October 12 to informed him that the two diplomats based in the Russian capital had been declared "personae non gratae."
Bulgaria is a NATO and European Union member with generally good ties with Russia, which supplies it with much of its energy.
But Sofia kicked out two Russian diplomats in January for allegedly pursuing classified information. It also declined to grant a visa to Russia's incoming defense attache in December 2019.
Bulgarian authorities declared the two Russian diplomats "personae non gratae" on September 23 after state prosecutors launched a case against them.
Criminal proceedings could not be brought against the suspects because they have diplomatic immunity.
The State Agency for National Security alleged the pair had collected secret state information on Bulgaria's military modernization plans and preparedness.
Investigators said the espionage took place between 2016 and the present, and included the use of financial inducements to recruit Bulgarian nationals with access to sensitive information.
The Russian Embassy in Sofia said there was no evidence to justify the "unreasonable expulsion" of its diplomats.