May 26 (UPI) -- The Estonian government expelled two Russian diplomats serving in the nation's third-largest city, though officials refused to say why.
The diplomats, consul general Dmitry Kazyonnov and consul Andrey Surgaev, who served at the Russian consulate in Narva, Estonia, are returning to Russia.
The Russian foreign ministry responded to its state-sponsored news agency RT that the incident was unfair.
The ministry said the expulsions are "yet another unfriendly and absolutely groundless act." Such actions from Tallinn "will not be left unanswered," it added.
Estonia and Russia have had frosty relations since the former Soviet republic gained its independence in 1991. Estonia is now a member of the western-aligned North Atlantic Treaty Organization.