Air travel across Europe was thrown into chaos on Wednesday as air traffic controllers went on strike against an EU plan to put the continent's air space under international controls.

Thirty-six hours we've got to wait. How sick are we about that?

UK passenger

Thousands of passengers had their travel plans disrupted as controllers in France, Italy, Portugal, Greece and Hungary walked out.

Hundreds of flights were cancelled or delayed. France was the worst hit.

Normally bustling airports stood empty as passengers heeded warnings to stay away, and there were reports of long queues at train stations as people looked for alternative transport.

"We've got a booking for tomorrow dinner time, can you believe that? Thirty-six hours we've got to wait. How sick are we about that?," one UK passenger told the BBC.

We are ready for further action, and why not this summer?

French trade union leader

The chaos has spread to countries not taking part in the strike, including Germany, where Frankfurt airport said it had cancelled 64 flights on Wednesday.

A general strike in Greece on Tuesday and another one planned in Spain for Thursday have further complicated the situation for travellers.

The air traffic controllers' union in France has warned there could be further strikes on the way if the EU does not rethink its proposals.

At-a-glance problems

Many countries are being badly hit, including:

• France Only 10% of short and medium-haul Air France services operating. British Airways running only four services out of 126 to France. Charles de Gaulle airport handling only 264 flights out of normal 2,000. At Orly airport, 77 out of 660 flights operating.
• Italy Fifty Alitalia flights cancelled, Air France cancels 22 of 23 flights from Rome.
• Germany More than 10% of Lufthansa flights to France cancelled, but long-haul services and domestic flights should remain unaffected. Frankfurt airport, Europe's second-busiest, cancelled 64 flights, mainly to and from the strike-hit countries.
• Spain Sixty Iberia flights to or from France cancelled, along with 57 domestic flights.
• Portugal Most airports at a standstill. Fifty-two flights cancelled by national airline TAP.
• Greece Fifty domestic flights and four international services cancelled.
• Netherlands Dozens of flights cancelled, including 20 KLM services to France. Other services facing hour-long delays, expected to worsen.

The French controllers are on strike from 0400GMT until 2000GMT. Controllers in Portugal, Italy, Greece and Hungary were stopping work for four hours on Wednesday from 1000GMT.

Long-haul flights through European airspace were likely to be less affected.

This is the worst possible time to be organising a strike

EU transport commissioner

And the strikes are due to end early enough on Wednesday to prevent any significant disruption to flights on Thursday.

The Single Skies plan which has sparked the protest would replace national air spaces with new zones of control based on international air corridors.

But the striking air traffic controllers believe the Single Skies system will lead to job losses and privatisation, and could compromise safety standards.

"We want safety to remain an absolute priority," union representative Sophie Coppin told the BBC from Charles de Gaulle airport in Paris.

Further strikes could take place, union leaders say.

Air traffic controllers oppose EU reform plans

"We are ready for further action, and why not this summer?" said French union leader Patrick Malandin.

European Commission officials insist the changes do not herald privatisation, and say the strike risks damaging European airlines just as they are beginning to recover from months of economic difficulties after 11 September.

"This is the worst possible time to be organising a strike," said EU Transport Commissioner Loyola de Palacio.

The commission estimates that the current system of air routings costs Europe 5bn euros ($4.7bn) annually in extra fuel, staff costs, and lost passenger time.

Spanish general strike

As the rest of Europe recovers from the strike on Thursday, Spain will be in the grip of a general strike.

Flights from Wednesday afternoon onwards are expected to be affected, as airlines will not want to risk their planes getting "stuck" during the strike.

Unions are taking action in protest against planned government reforms to the unemployment system.