Polish state-owned airline LOT suffers hacking assault on airport ground systems that causes 10 national and international flights to be cancelled.

Around 1,400 passengers of the Polish airline LOT have been grounded at Warsaw Chopin airport after hackers attacked the airline ground computer systems used to issue flight plans, the company said.

The computer system was hacked on Sunday afternoon and fixed after about five hours, during which 10 of the state-owned carrier’s national and international flights were cancelled and about a dozen more delayed, spokesman Adrian Kubicki said.

LOT was taking care of the passengers on Sunday evening and some were already able to board flights. The airline said it was providing hotels for those who needed to stay overnight.

At no point was the safety of ongoing flights compromised, Kubicki said, and flights destined for Warsaw were able to land safely. No other airports were affected, he added.

“We’re using state-of-the-art computer systems, so this could potentially be a threat to others in the industry,” Kubicki said. The attack is now being investigated by the authorities.

The airport itself was not affected, its spokesman said.

The airline said it expected to release the aircraft – which was due to fly to Oslo – and reopen the airport shortly.

“This was an irresponsible prank,” Mariusz Mrozek, a police spokesman, told Polish broadcaster TVN24.

The flight landed on Thursday morning at Modlin – a small, auxiliary airport in Warsaw used only by Ryanair – from Oslo and was due to return to Norway later in the day.

A spokesman for the Ryanair said: “Warsaw Modlin Airport received an anonymous call that there was an explosive device on a Ryanair aircraft due to take off from Modlin to Oslo at 08.40hrs local.

“The airport security authorities ordered an immediate inspection of the aircraft (which hadn’t yet boarded) and closed the airport to inbound arrivals as a security precaution.

“Warsaw Modlin believes this is a hoax call and expects the security sweep to confirm this fact.

“They expect to release the aircraft and reopen the airport shortly. Ryanair sincerely apologises to the customers of the outbound Oslo flight for any inconvenience caused by this hoax call.”