Russian airline Aeroflot cancelled dozens of flights on Monday after what it called a failure in its information systems, and a shadowy hacking group claimed responsibility for what it said was a crippling cyberattack.
The national carrier did not provide further details about the cause of the problem or how long it would take to resolve.
A statement purporting to be from a hacking group called Silent Crow said it had carried out the operation together with a Belarusian group called Cyberpartisans BY, and linked it to the war in Ukraine.
"Glory to Ukraine! Long live Belarus!" said the statement, whose authenticity Reuters could not immediately verify.
Silent Crow previously claimed responsibility for an attack on a Russian real estate database in January.
Aeroflot said it had cancelled more than 40 flights after reporting a failure in its information systems.
Since Russia launched the war in Ukraine in February 2022, travellers in Russia have become accustomed to flight disruptions. However, those delays have usually been caused by temporary airport closures after drone attacks.
Aeroflot said: "Specialists are currently working to minimize the impact on the flight schedule and to restore normal service operations."
On Telegram, it listed more than 40 cancelled flights to destinations across Russia, as well as to the Belarusian capital Minsk and the Armenian capital Yerevan.
Aeroflot urged passengers whose flights from Moscow's Sheremetyevo airport had been cancelled to retrieve their checked-in luggage and leave.
News outlet Baza reported scenes of chaos at the airport, with logjams forming as passengers queued just to get out.
The statement in the name of Silent Crow said the cyberattack was the fruit of a yearlong operation that had deeply penetrated Aeroflot's network, destroyed 7,000 servers and gained control over the personal computers of employees, including senior managers. It did not provide evidence of those claims.
It threatened to shortly start releasing "the personal data of all Russians who have ever flown Aeroflot."
Aeroflot, which despite sanctions imposed on Russia for its war in Ukraine that have drastically limited travel and routes, remains among the top 20 airlines worldwide by passenger numbers.
In 2024, passenger traffic of the Aeroflot Group reached 55.3 million passengers, according to the airline's website.
