In a co-ordinated move, four EU countries are expelling more than 40 Russian diplomats suspected of spying.
Ireland, Belgium, the Netherlands and the Czech Republic issued expulsion orders to a total of 43 embassy staffers on Tuesday afternoon.
The move follow similar actions taken by other EU members, including Poland, in the past week.
Belgian Foreign Minister Sophie Wilmes told MPs that the expulsions were “related to our national security”.
Speaking to parliament, Ms Wilmes said that 21 members of staff at the Russian embassy in Brussels and at the consulate in Antwerp had been asked to leave the country, giving them two weeks to depart.
She added that the move was made in conjunction with Belgium’s neighbour the Netherlands, whose foreign ministry said it was expelling 17 Russian diplomats it considered to be “secretly active” as intelligence officers.
Ireland’s Taoiseach (Prime Minister), Micheál Martin, told MPs that his government had expelled four Russian diplomats after receiving security advice from its intelligence officials.
Mr Martin said the officials had been asked to leave the state “because their activities are not in accordance with the international standards of diplomatic behaviour”.
Russia’s embassy in Dublin said it rejected the “groundless decision,” adding that it would “deteriorate further Russian-Irish relations”.
Meanwhile, a Czech official told the AFP news agency that the diplomat expelled from Prague was Russia’s deputy ambassador.
“Together with our Allies, we are reducing the Russian intelligence presence in the EU,” the Czech foreign ministry tweeted.
On Wednesday, Poland expelled 45 accredited diplomats for engaging in suspected espionage in the country.
The Polish Interior Minister Mariusz Kaminski wrote on Twitter that Polish intelligence officials were “dismantling the Russian special services network in our country”.
And earlier this month Bulgaria, Lithuania, Latvia and Estonia expelled a total of 20 Russian embassy staffers in connection with activities “contrary to their diplomatic status”.
Russia has tended to respond to such decisions with reciprocal moves, and earlier today announced the expulsion of 10 diplomats from Estonia, Latvia and Lithuania.