BA said that the cancellations were all pre-planned and passengers were given a notice of a week or two. easyJet has also cancelled a lot of flights.
British tourists must have at least three months validity on their passport if they want to travel to the EU.
The post-Brexit rule has caught out some Britons as many are unaware of the strict passport regulations.
Following Brexit, Britons can only travel to the bloc with a passport that was issued less than 10 years ago.
They must also get their passport stamped on entry and exit to the EU. There are fears this could lead to chaos this summer.