Travel chaos for Britons returning from Christmas holidays as Greece shuts airspace and ALL flights suspended

The disruption began in the morning and quickly escalated, impacting dozens of flights.

Some overflights across Greek and regional airspace were still being serviced, but restrictions were imposed on airport operations for safety reasons, Greece's civil aviation authority said.

"For some reason all frequencies were suddenly lost," Panagiotis Psarros, chair of the Association of Greek Air Traffic Controllers, told local media.

"We could not communicate with aircraft in the sky."

He said the problem appeared to be a collapse of central radio frequency systems at the Athens and Macedonia area control systems, the largest air control facility in the country based in Athens.

The facility is responsible for monitoring the Athens Flight Information Region, a vast expanse of airspace under the control of Greek authorities.

Flight trackers showed Greek airspace was largely empty.

Local media said airport arrivals and departures were suspended at 9am local time (7am GMT).

"We haven't been informed about the cause of this problem... certainly the equipment we have is virtually ancient," Mr Psarros said.

A Transport Ministry official said some aircraft heading north and east were allowed to leave.

More than 75 flights were delayed, the official said.

Athens International Airport, which is the largest in Greece and one of the biggest in Europe, is among those impacted by the disruption.

Last year, it recorded passenger numbers of more than 31 million.

Flights departing from the airport are currently either delayed or cancelled.

In a statement on social media, Athens Airport said: "The Hellenic Aviation Service Provider started gradual release of some flights in accordance with the Air Traffic Control capacity availability.

"Efforts for full restoration of the technical issues are continued.

"For further information regarding your flight, you can follow airline’s announcement and updates."