More than 400 flights affecting tens of thousands of travellers were grounded across Europe while airlines faced severe delays and detours of flights during the first day of a strike by French Air Traffic controllers.

Even more cancellations are expected today when Marseille air traffic zone will be involved in addition to the Brest and Bordeaux sectors, lobby group Airlines for Europe (A4E) warned.

Beside cancellations, airlines were forcing into lengthy diversions due to the walkout by controllers in France which is due to run until Friday.

A flight from Frankfurt to Lisbon had to divert via south-west England and a service from the Canary Islands to Copenhagen nearly reached the Irish coastline.

The most affected countries besides France were the UK, Spain, Italy and Ireland. Ryanair confirmed that is has been forced to cancel more than 80 flights today, almost double the 45 cancellations yesterday.

“We sincerely apologise to all customers whose travel plans are being disrupted by these unjustified strikes, who have been contacted by email and SMS text message and advised of their options,” a spokesman said.

“The strike may also affect flights overflying France and we expect some flight delays and possible further cancellations.

“Customers scheduled to fly on Tuesday should check the status of their flight on the home page of the website – where updates will be published – before travelling to the airport and allow extra time for their journey.”

British Airways, which is also facing a strike by Unite cabin crew members of its mixed fleet until Thursday, said the French Civil Aviation Authority has mandated the cancellation of a number of flights for all airlines using French airspace.

“Unfortunately, in addition to cancelling some flights to and from France, other short haul flights may also experience some disruption given how many flights would normally use French airspace,” the airline said.

“We are still assessing which services may be affected on each day of industrial action, but we recognise the uncertainty the situation is causing and have introduced a more flexible rebooking policy.

“We will be using larger aircraft, where possible, to help affected customers and are doing all we can to reduce the levels of disruption.

“Given that the situation could change at very short notice, we will aim to publish any revisions to our schedule the day before each strike day.”

EasyJet said: “We are working to minimise the impact of the strike, but like other airlines flying to and from France there will be cancellations and potential delays.”

Flybe cancelled eight flights yesterday and six today including services to and from Paris from Manchester and Southampton.

Air France warned that about a quarter of domestic flights from Paris Orly and the French provinces to be affected today, however it expects more than 93% of short and medium haul flights to operate from Paris Charles de Gaulle and all long haul services.