The small east European nation of Moldova summoned the Russian ambassador on Wednesday to declare a member of embassy staff persona non grata, prompting Moscow to complain.
Government press secretary Daniel Voda told reporters the decision was connected to the actions of embassy staff towards Moldovan border guards who denied entry to a regional Russian politician at Chisinau airport this week.
Moldova, which applied to join the European Union last year alongside its neighbour Ukraine, has repeatedly accused Russia of trying to destabilise the country, something Moscow denies.
Moldova told Russian politicians not to meddle in its internal affairs on Monday after barring Rustam Minnikhanov, governor of Russia's Tatarstan region. Police said he aimed to bolster support for a pro-Russian candidate standing in a regional election.
Russian ambassador Oleg Vasnetsov said he had not received answers to why the embassy employee was being kicked out and why Minnikhanov had been barred.
"We consider these actions to be unfriendly steps towards our country," he told reporters.
(Reporting by Alexander Tanas, writing by Max Hunder and David Ljunggren; Editing by Timothy Heritage and Grant McCool)