We are doing all we can to minimise the disruption to our customers.
Customers due to fly to or from Spain today can rebook to an alternate date free of charge. Customers on cancelled services can also take a full refund.
We are also looking at putting on larger aircraft to help as many customers as possible. We are advising customers to check ba.com for the latest flight information.
We apologise to our customers for any inconvenience caused by industrial action which is beyond our control.
Heathrow Airport has said 39 flights - nearly all involving Spain or Portugal - had been cancelled today at the west London airport, as a result of strike action across Europe.
Most people seem to have got the message that some flights were going to be axed and the terminals are operating smoothly.
Flight cancellations are never good news, but we do operate around 1,300 flights a day so the figure of 39 is a comparatively small one.
There may be some delays today due to the strikes in continental Europe. Please check with your airline or airline website.
Due to strikes in Spain, Greece & Portugal tomorrow, some flights may be disrupted. Please check with your airline for the latest info.
Air passengers endured travel misery today as UK airlines cancelled flights due to anti-austerity strikes across Europe.
British Airways had to axe eight round-trip flights between London and Madrid and Barcelona, as well as two return services to Lisbon in Portugal.
EasyJet cancelled some UK-Spanish services as well as more than 20 within-Europe flights.
Some other easyJet flights were badly delayed - with a London service to Thessalonaki in Greece delayed for three hours 40 minutes.
Passengers on an easyJet London to Athens flight faced a delay of two hours 30 minutes, while a Manchester-Athens flight was delayed for two hours 10 minutes.
Heathrow and Gatwick were among the UK airports where flights were delayed or cancelled.
The interior ministry said 32 people had been arrested and 15 people treated for minor injuries following disturbances in Spain, as strikes and protests against austerity measures took place across Europe.
The General Workers Union said the stoppage, the second in Spain this year, was being heeded by nearly 100% of workers in the motor, energy, shipbuilding and construction industries.
But ministry official Cristina Diaz played down participation, saying it was hardly noticeable in goods haulage and major city wholesale food markets.
She said electricity consumption, a gauge of industrial activity, was down 11% on a normal working day.
With a 25% unemployment rate, Spain is at the core of Europe's debt crisis.
Strikers have been arrested in Madrid, as a series of coordinated anti-austerity strikes take place across Europe. Union-organised action in Spain and Portugal is expected to be followed by demonstrations later in Italy, Malta, Cyprus and Greece.
Transport is expected to be disrupted, schools and public services closed and rallies held across the continent to protest over spending cuts, tax hikes and workers' rights.
The ETUC strongly opposes the austerity measures which are plunging Europe into economic stagnation, recession, and dismantling the European social model. These measures, far from restoring confidence, are only aggravating imbalances and creating injustices.
Workers in Spain and Portugal are taking part in general strikes today in protest against anti-austerity policies being implemented by governments in both countries.