Moldova's authorities and an opposition politician said Friday aviation officials had denied landing permission to a flight bound for the capital Chisinau carrying pro-Russian opposition activists.
According to Romanian authorities, the flight from Armenia was redirected to an airport near the capital Bucharest.
Moldovan pro-Russian MP Marina Tauber announced the incident in a post on Telegram.
"Chisinau airport refused to allow a flight from Moscow via Yerevan carrying participants in the congress of the Moldovan opposition political bloc 'Victory' to land," she wrote.
"The aircraft was diverted to Bucharest."
Low-cost carrier FlyOne failed to "notify [flight] schedule changes three days in advance as required by law," Moldova's Civil Aviation Authority said in a Facebook post Friday.
A source at Otopeni airport near Bucharest confirmed to AFP that an aircraft with 174 passengers on board landed there on Friday morning.
Once there, the plane was checked following a bomb threat that turned out to be a false alarm, the source added.
Videos posted by Tauber on Telegram showed passengers getting off the FlyOne flight for identity checks.
The incident came a day after the United States, Britain and Canada warned of a Russian "plot" to influence Moldova's presidential elections this autumn.
Their joint statement published on Thursday said they feared Moscow would "incite protests" if a pro-Russian candidate failed to win in the country.
In late April, Moldovan pro-Russian opposition parties gathered in Moscow to announce the formation of the "Victory" political bloc, ahead of the presidential elections and an EU membership referendum in October.
Moldova, led by pro-European President Maia Sandu, frequently accuses the Kremlin of interfering in its internal affairs.
Sandu has accused Moscow of trying to stoke tensions in the former Soviet republic of 2.6 million people.
In the run-up to the presidential election on October 20, in which Sandu is seeking a second term, the political situation has been especially tense.
Wedged between war-torn Ukraine and EU member Romania, Moldova has been an official candidate to join the European Union since June 2022, just months after Moscow launched its invasion of Ukraine.
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