Prague expelled a number of Russian diplomats this month, with Slovakia and the Baltic states of Estonia, Latvia, and Lithuania following suit in solidarity
Moscow on Wednesday expelled seven European diplomats after their countries ordered Russian diplomats to leave in solidarity with the Czech Republic, which is engulfed in a diplomatic row with Russia.
The Czech government this month accused Russian secret services of being behind a deadly explosion at an arms depot in the eastern Czech Republic in 2014.
It expelled a number of Russian diplomats over the allegations, with Slovakia and the Baltic states of Estonia, Latvia, and Lithuania following suit in solidarity.
Russia's foreign ministry on Tuesday said in a statement that a total of four diplomats from Estonia, Latvia, and Lithuania have been declared "persona non grata" and must leave the country within seven days.
It added that the Baltic states "continue to conduct an openly hostile course towards our country, in this case hiding behind pseudo solidarity with the indiscriminate actions of the Czech Republic towards Russia".
In a separate statement, the ministry also announced the expulsion of three Slovak diplomats, who must leave by May 5, and accused Bratislava of "false solidarity" with Prague.
Slovakia's actions "damage the traditionally friendly Russian-Slovak relations and constructive bilateral cooperation," the statement added.
Earlier this month, Prague expelled 18 Russian diplomats over the spy allegations.
Moscow retaliated by kicking out 20 Czech embassy staff and both sides imposed a ceiling on embassy workers, meaning dozens more will have to leave by next month.
The Czech Republic also asked its partners in the European Union and Nato to expel Russian diplomats in solidarity.
Slovakia, which formed a single country with the Czech Republic until 1993, expelled three Russian diplomats, while the Baltic states, which were once part of the Soviet Union, ordered four Russian diplomats to return to Moscow.