Two F-16 jets escorted the flight, which took off from Katowice for Athens, as it entered Greek airspace from North Macedonia, the source told AFP.

The Boeing 737 had earlier been escorted by Hungarian warplanes, the official added.

The flight finally landed at an isolated area at Athens International Airport shortly before 1600 GMT, a delay of nearly two-and-a-half hours.

"The passengers have disembarked and are being inspected," Greek police spokeswoman Constantia Dimoglidou told AFP.

"There were 190 people on board including the crew. The plane will be checked after the passengers," she said.

As the plane approached Athens, it was diverted over the sea as a precaution.

Piotr Adamczyk, public relations manager at Katowice airport, said they had received a telephone warning as the plane was flying over Slovakia.

"After the plane took off, there was a call to the airport information centre concerning the possible presence of an explosive device on board," Adamczyk told AFP.

"We contacted air traffic control, which subsequently contacted the pilots," he added.

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