A radio frequency problem severely disturbed the air traffic in Greece on Sunday morning.
In a statement, the country's civil aviation authority said some frequencies that serve the Athens FIR (Flight information region) have faced problems, which eventually led to restrictions on air traffic across the country's international and regional airports.
Public broadcaster ERT confirmed that the technical problem affected all flights to and from the country, adding that work to restore air traffic was underway.
The Kathimerini newspaper, meanwhile, reported that preliminary reports pointed to a circuit failure.
The precise cause or origin of the problem, however, has not yet been determined, the paper said, adding it is not clear when normal operations will be restored.
