Flights around western Europe are facing more disruption due to another strike by French air traffic controllers.
Unions were due to take action during a national strike across France from 6pm on Monday (June 13) to 5am on Wednesday (June 15).
UK-based airlines have warned passengers about potential disruption on Tuesday, June 14, while airline organistion Airlines for Europe (A4E) said the strike would lead to "100 flight cancellations and many delays".
British Airways said the strike would “bring yet another day of unnecessary disruption for some customers travelling in Europe”.
“This strike will be the ninth day of industrial action in the past three months by French air traffic controllers,” said BA in an online post to customers.
“We are sorry that your flight could face disruption, which is beyond our control, and we recognise that you may not wish to travel as a result.”
Easyjet added: "Like all airlines, our flights to and from French airports, as well as those flying in French airspace, could be affected.
"We are doing everything possible to minimise the impact of the strike on our customers, and we advise all passengers to allow plenty of extra time to get to the airport and consider alternative transport options where possible, as public transport services may be affected by the strike."
Air France is also being affected by a separate four-day strike by its pilots, while Easyjet is facing stoppages at Amsterdam on Tuesday (June 14) due to a dispute with the VNV pilots’ union in the Netherlands.
Thomas Reynaert, managing director of A4E, said: "We are reaching a pathetic milestone: more than 50 ATC strikes in France over the last seven years which account for more than 150 days of disruption.
"Understandably, European passengers and airlines are frustrated as these strikes take place at a very busy time of the year. The European Commission and governments must act immediately to protect the rights of millions of European travellers affected by this repeated and disproportionate industrial action."