An IT failure may have triggered a computer systems meltdown at Polish flagship carrier LOT that grounded more than 1,400 passengers at Warsaw's Frederic Chopin Airport at the weekend, Polish prosecutors said Wednesday.
The airline's spokesman had initially described Sunday's incident as the "first attack of its kind", suggesting a cyber-attack.
But Poland's PAP press agency on Wednesday quoted unofficial sources as saying a report by Poland's Internal Security Agency (ABW) report revealed that human error had triggered the failure.
"We are currently checking if there is justified suspicion of a remote computer attack, or if the incident was caused by a systems failure. All possibilities are being examined," Przemyslaw Nowak, a spokesman for Warsaw district prosecutors was quoted as saying by PAP.
Poland's ABW confirmed it had forwarded a report on the incident to prosecutors, but refused to disclose its contents.
The incident occurred at around 4:00 pm (1500 GMT) on Sunday and lasted five hours shutting down the airline's ground operations system.
A dozen domestic and international flights had to be cancelled and delayed before air traffic could resume.
Concerns around aviation and hacking are on the rise, compounded by a new wave of airliners connected to the Internet which has prompted fears that cyber-terrorists could take control of planes remotely.