There has been widespread chaos across Europe following a series of strikes on Wednesday by many of the continent's air traffic controllers.

Thousands of flights have been cancelled and many travellers subjected to massive delays.

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

UK passenger

Workers in France, Italy, Portugal, Greece and Hungary walked out to protest against the Single Skies scheme - a European Union project to bring airspace under a single authority.

They say the scheme will lead to job losses and privatisation, and could compromise safety standards.

Controllers in France - the country with the largest and most instrumental airspace in Europe - led the action and continued to strike after their colleagues abroad had wrapped up their four-hour protest.

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.

Flights to Spain have also been affected in anticipation of a general strike to protest against planned government reforms to the unemployment system.

Airlines are keen to avoid their aircraft being stuck in the country when the strike takes hold on Thursday.

At-a-glance problems

Many countries were being badly hit, including:

• France Only 10% of short and medium-haul Air France services have been operating. British Airways ran only four services out of 126 to France. Charles de Gaulle airport handled only 264 flights out of normal 2,000. At Orly airport, 77 out of 660 flights operated.
• 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 thought to be 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.

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

This is the worst possible time to be organising a strike

EU transport commissioner

Most long-haul flights through European airspace, however, were not affected.

The strikes are not expected to lead to any significant disruption to flights on Thursday.

But 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.

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

Air traffic controllers oppose EU reform plans

European Commission officials insist the Single Skies plan does 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.