A technical problem prevented flights from taking off at Greek airports on Sunday morning, aviation authorities said.

'There is a problem with communications between the various control towers. All departures have been halted,' said a spokeswoman at Athens' Eleftherios Venizelos airport. 'Flights can land normally,' she told the German Press Agency dpa.

The secretary-general of the Greek air traffic controllers union, Giannis Kormoulakis, described the situation as 'chaotic.' 'The entire communications network is down,' he told Greek radio. 'All departing flights have been halted.' Kormoulakis said the problem was due to 'years of neglecting to modernize the technical equipment for airspace surveillance.'

Officials said a back-up system was being used for contact between the flight-control towers, but this had a limited capacity.

It was not immediately clear how long it would take to fix the malfunction.

On Friday, A technical malfunction at Europe's joint air traffic control agency, Eurocontrol, disrupted 700 flights over northern Europe.