Several Greek domestic and international flights were cancelled on Wednesday as air traffic controllers went on strike at the height of the tourism season, asking for European-based reforms to be brought in to civil aviation services.
At Athens airport, Greece's biggest, about 22 flights were called off and 173 rescheduled due to the four-hour stoppage, said an airport spokeswoman.
The civil aviation authority said it could not provide figures on how many flights were cancelled across the country but had informed passengers about possible delays.
The controllers, who are striking from 1100 to 1500 GMT, want their government agency to be restructured and an independent one set up in line with European Union rules.
They say that this will help the country deal with staff shortages and a lack of funds for the maintenance of air traffic control systems.
Cash-strapped Greece is struggling to clinch a new bailout deal with its international lenders to stay afloat in the euro zone and get its economy back on its feet.
Tourism is a major cash earner, accounting for about one fifth of Greece's economic output.
The air traffic controller's union has threatened to step up action from Aug. 14 if the government does not respond to its demands.