UK airlines were forced to cancel over 100 flights to and from France today due to strikes by French air traffic controllers.

With British Airways and easyJet operating only a skeleton service, Channel Tunnel operator Eurotunnel put on extra trains to cope with increased passenger demand, while P&O Ferries reported large numbers using its Dover to Calais vessels.

The industrial action was part of a public sector workers' protest against France's plans to reform pension arrangements. Further strikes could affect travel early next week, with possible days of action on June 2 and 3.

British Airways said they were using larger aircraft where possible. EasyJet, which flies to Paris, Nice and Lyon, said passengers affected could get a full refund or transfer to a flight on another day.

Fewer than 900 planes were expected to take off or land in France during the day, compared to a normal daily total of more than 4,000.

As well as air traffic controllers, French teachers, postal and telecoms employees, and Marseille's port workers were also going on strike today. Union leaders have threatened to press on with more strikes unless France's centre-right government under prime minister Jean-Pierre Raffarin backs off from its pension reform plans.

The government wants to increase the number of years employees must work to get a full pension at retirement. It claims the current system will collapse within 20 years if nothing is done.