Russia will expel two Greek diplomats in response to Athens' decision to throw out two of Moscow's envoys, Russian news agency RIA reported on Wednesday, citing a senior lawmaker.
Greek media reported earlier that Athens had decided to expel the Russian envoys and ban entry to another two over suspicions they had tried to undermine an agreement with neighbouring Macedonia.
The Greek government did not respond directly to the reports but its spokesman said it would not tolerate any behaviour which violates international law. None of the reports said whether the expulsions had actually taken place, although the Greek spokesman suggested some kind of action had been taken.
Greece's Kathimerini newspaper said Athens authorities ordered the expulsions after suspected attempts by the Russian diplomats to undermine an agreement Greece brokered with the former Yugoslav republic of Macedonia last month which ended a decades-old diplomatic standoff over its name.
The deal between Greece and Macedonia is expected to ease the admission of the small but strategically-important state into NATO, in a region where Russia and the West are jostling for influence.
Kathimerini said Greek authorities were investigating intrusion into domestic policy issues and quoted diplomatic sources as saying the suspicions were solely focussed on those four individuals. Greece's Skai TV also reported Athens had decided to expel the Russians.
A member of Russia's upper house of parliament, Andrei Klimov, said Russia would expel two Greek diplomats in response, without mentioning Macedonia or going into further detail about the reasons for the actions.
Greek government spokesman Dimitris Tzanakopoulos did not comment on the Russian report but said: "Greece has proven as part of a multifaceted foreign policy that it seeks good relations with all states. From there on, all states and authorities should respect international law, but also us, the Greek government and the Greek state."
"It is within that framework, and whenever required, measures have been taken. That has also occurred this time," Tzanakopoulos said.
Greece has long said Macedonia's name implies a territorial claim over its northern province with the same name, and has previously blocked its neighbour's attempts to join NATO.
After a period of political crisis, the two governments have agreed name of Republic of North Macedonia, though that still has to be put to a referendum in the Balkan state.