"We will, so to speak, respond in an appropriate manner. Possibly with non-symmetrical measures. But the answer will be provided", Mitrofanova said on air of Russia-24 TV channel.
The Bulgarian authorities did not explain the reasons for expelling the Russian diplomats, Mitrofanova added.
On Friday, Bulgaria declared ten Russian diplomats personae non gratae. Latvia and Estonia also announced that they have decided to expel three employees of the Russian embassies in their countries, while Lithuania has expelled four.