Bulgaria's Foreign Ministry on Friday announced the expulsion of 10 Russian diplomats for breaching international conventions on diplomatic ties.

The wording used by the ministry hinted toward espionage. Sofia expelled two Russian diplomats earlier this month for similar reasons.

The European Union and NATO member has strong economic ties with Russia but several alleged cases of espionage have strained the relations since October 2019.

The latest expulsions come as relations between the West and Moscow hit a new low over Russia's invasion of Ukraine, which has spawned unprecedented sanctions and seen Moscow diplomatically isolated.

Baltic countries Estonia, Latvia and Lithuania on Friday announced the expulsion of 10 Russian diplomats over Moscow's invasion of Ukraine, following in the steps of Bulgaria.

"Latvia expels three Russian Embassy employees in connection with activities that are contrary to their diplomatic status and taking into account ongoing Russian aggression in #Ukraine. The decision has been coordinated with #Lithuania and #Estonia," Latvian Foreign Minister Edgars Rinkevics tweeted.

Estonia has also expelled three diplomats and Lithuania four, according to their foreign ministries.

The Russian Embassy in Sofia said on Friday that 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.