Polish authorities said they had fixed a fault in air traffic control systems that briefly disrupted take-offs in Warsaw and other cities on Saturday morning, and operations were returning to normal.
Warsaw's Chopin Airport said take-offs and landings were running as usual by midday. Earlier outages had forced authorities to limit the number of flights in Polish airspace.
Airports in Krakow, Katowice and Gdansk had also reported issues through the morning.
"The temporary problems were caused by a fault that was promptly resolved," the Polish Air Navigation Services Agency (PANSA) wrote in a statement, without providing further details on the fault.
"After implementing all necessary procedures, the primary air traffic management system was restored," the agency said. Backups had kept safety systems running through the outage, it added.
Earlier, the Interior Ministry said the security agency had investigated the outage and made routine checks for sabotage.
Poland and other countries have accused Russia of stepping up disruption and sabotage campaigns since its invasion of Ukraine in February 2022 - accusations that Moscow has denied.
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