Romanian authorities have declared the Russian embassy's deputy military attache, Alexei Grichayev, a persona non grata on Romanian territory, a Foreign Ministry official told local press agency Agerpress.

Romanian Minister of Foreign Affairs Bogdan Aurescu informed the Russian ambassador in Bucharest of the decision in a meeting on Monday.

The step to remove the Russian official was taken in solidarity with the Czech Republic, which is involved in a spat with Moscow, AFP reported.

The Foreign Ministry defended its decision to remove Grishaev from the country in a statement to Agerpress that said "his activities and actions contravene the provisions of the Vienna Convention on the Law of Treaties of 1969."

Russia's souring relations with Eastern Europe

The decision in Bucharest follows an escalating diplomatic row over the alleged role of Russian spies in a deadly blast at a Czech munitions depot in 2014. It is the worst dispute between Moscow and Prague in decades.

Czech Foreign Minister Jakub Kulhanek said Moscow would have until the end of May to withdraw 63 embassy employees, a move he said aimed to bring staff numbers in line with those at the Czech Embassy in Russia.

NATO allies Slovakia, Estonia, Latvia and Lithuania all announced that they were expelling Russian diplomats — seven in total — after Czech Interior Minister Jan Hamacek asked for solidarity from the country's European neighbors.