Earlier this week people threw red paint on the Russian Embassy in Prague in protest against the war in Ukraine. (Photo: AFP)

Four European nations have expelled Russian diplomats or agents for alleged spying.

Belgium told 21 Russian diplomats they have two weeks to leave the country after they were judged to be a danger to national security.

Belgium's neighbour Netherlands expelled 17 Russians who were in the country on diplomatic visas, but were "secretly active as intelligence officers" according to the Ministry of Foreign Affairs.

The Republic of Ireland has asked four "senior officials" to leave the state, but its foreign ministry did not expand on the reason for the expulsion.

Czechia has also expelled a single diplomat, giving them just 72 hours to leave.

"Together with our allies, we are reducing the Russian intelligence presence in the EU," the Ministry of Foreign Affairs in Prague said.

All four countries which have published diplomatic expulsions today are EU members.

Belgium's Foreign Minister Sophie Wilmes reassured citizens that the country's move did not signal an end to diplomatic relations and communication channels with Moscow.

"Diplomatic channels remain open with Russia, the Russian Embassy can continue to operate and we continue to advocate dialogue," she affirmed.

Ireland's Taoiseach Micheal Martin confirmed the action was coordinated between the four European Union member states.

"We've done it with some countries today, in terms of these measures with officials, working with other countries on this initiative," he told the Irish Dail (parliament).

Although he suggested there was hope it would be a wider action, only four members agreed to the plan.

"It hasn't been possible to get the full 27 (EU member states) working on the same sort of agenda," Martin added.

Russia's Embassy in Dublin reacted to the expulsion calling it an "arbitrary, groundless decision, which can only deteriorate further Russian-Irish relations."