Flights are likely to be disrupted for three days as a result of the Europe-wide general strike to begin on Wednesday.
The European Trade Union Confederation (ETUC) strike action has been backed by unions in Greece, Portugal, Spain and the Canary Islands.
Passengers booked to fly on all affected European sectors should check the updates on their airline's website.
EasyJet has cancelled 26 flights, including services from Gatwick to Barcelona and Madrid, and re-scheduled 10 others, including flights from Gatwick and Manchester to Athens and from Gatwick to Thessaloniki.
TAP Portugal has announced that London to Lisbon flights will also be affected today and 15 November. Many flights have been cancelled or delayed including Gatwick to Oporto and Manchester to Lisbon.
Most airlines have urged passengers to re-book free of charge for alternative dates. EasyJet said: "We regret this situation and are doing our utmost to reduce the inconvenience caused by this action".
Ryanair has listed some flights which the Spanish government has 'guaranteed' will not be cancelled but may be delayed on its website. It says the position is still under review and passengers should check for updates. Those on affected routes can change their dates.
British Airways also said passengers due to travel to or from Spain on Wednesday can change to another date free of charge and has warned there could be disruptions on services to other European countries.
Different countries will be affected at different times at workers in Spain and the Canaries are expected to walk out from midnight tonight until midnight on Wednesday but in Greece the strike is only expected to last from mid-day tomorrow until 15:00hrs.
A spokesman said BA believed the strike would only affect Spanish routes and that it will be putting on larger aircraft to help as many customers as possible.
The Iberia Group has said it's cancelled more than 350 flights including Madrid to London as a result of the strike which affects air traffic control workers.
The strike is in protest of the austerity measures being imposed on many Europeans and what they claim is an overthrow of labour rights and national collective bargains.
The Foreign Office said on its website: "Public transport within Spain and services at Spanish airports are likely to be significantly disrupted and public demonstrations in city centres may also affect local services on the 14 and 15 November."
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