The Russian Foreign Ministry has declared a staffer of the Bulgarian Embassy persona non grata, responding to Sofia's expulsion of a Russian diplomat last month in a move Moscow condemned as unjustified.
The ministry announced in a statement that it had notified Bulgarian Ambassador Atanas Krastin of the ministry's decision.
Bulgaria's Ministry of Foreign Affairs said in late April it had declared a Russian diplomat persona non grata. Moscow vowed to retaliate in kind.
Bulgarian media outlets previously reported that six Russian citizens were suspected of being involved in a series of blasts at factories and arms depots - three of whom were charged with the attempted murder of Bulgarian businessman Emilian Gebrev. Bulgarian prosecutors are now looking into four alleged explosions at arms depots between 2011 and 2020.