"The Russian side reserves the right to retaliate," the embassy added.
On March 22, the Bulgarian Foreign Ministry declared two employees of the Russian Embassy in Sofia persona non grata.
Before that, the Prime Minister of Bulgaria Boyko Borisov announced his readiness to declare Russian diplomats persona non grata because of the espionage case.
In turn, Russian Deputy Foreign Minister Alexander Grushko said that "if Bulgaria takes unfriendly steps towards Russia, then, naturally, they should understand" that retaliatory actions will follow.