The Russian embassy to Sofia said on Friday Bulgaria's decision to expel 10 Russian diplomats was "yet another aggressive step" to which Moscow would respond accordingly.
In a statement on its Telegram channel, the embassy said it saw the expulsions as a sign of Bulgaria's intention to cut Bulgarian-Russian relations to a minimum.
"This hostile demarche will soon get a relevant appraisal and a reaction, adequate to the new spirit of the bilateral relations," the embassy said.