MOSCOW (Reuters) - Moscow on Thursday expressed regret at Bulgaria's decision to declare two Russian diplomats 'persona non grata' and promised details on retaliatory measures at a later date, the foreign ministry said in a statement.
Bulgaria on Wednesday said it had expelled two Russian diplomats who prosecutors suspect were involved in spying, giving them 72 hours to leave the Balkan country, a move the Russian Embassy in Sofia described as "groundless".
(Reporting by Maxim Rodionov; Writing by Alexander Marrow; Editing by Toby Chopra)
