Russia’s Pulkovo Airport in St. Petersburg temporarily suspended all flights on Tuesday, the city government said.
It did not provide a reason.
An unconfirmed media report from online Russian news outlet Baza said an unidentified object had been spotted in the sky and that fighter jets had been dispatched to investigate.
Reuters could not immediately confirm the report.
Data from the Flight Radar website showed a number of domestic flights headed for St Petersburg turning back to their destinations.