Russia said on Tuesday it was expelling 36 diplomats from two European countries in retaliation for similar measures taken against Moscow's foreign envoys over the Kremlin's military operation in Ukraine.

The Russian foreign ministry said it had declared 21 diplomats from Belgium and 15 from the Netherlands "persona non grata", giving them two weeks to leave.

Moscow also summoned Luxembourg's envoy, Georges Faber, warning him that Russia may decide to take reciprocal measures for the tiny European state's expulsion of Moscow's ambassador.

Moscow further gave four Austrian diplomats until Sunday to leave Russia, underscoring a break in relations with a country that had enjoyed relative neutrality since the Cold War, saying the expulsion of four Russians "seriously damaged both bilateral relations and Austria's international prestige".

The expulsions are the latest in a series of measures taken between Moscow and Western countries in the wake of Russia's military campaign.

The offensive has thrown Russia into international isolation and broken many of its economic ties with the West.

But Russia has still not responded to decisions by Germany and France to each send home 40 of Moscow's envoys, meaning that more expulsions were likely soon.

The Russian foreign ministry called a decision by the Netherlands to expel 18 Moscow envoys on March 29 "groundless".

It called a similar step taken by Belgium "provocative", and the decision by Luxembourg "an unmotivated and unfriendly step".