The travel plans of hundreds of passengers flying between the UK and Spain were thrown into disarray today as a Spanish pilots' union called a seven-day strike.

Spanish carrier Iberia, which jointly markets some flights with British Airways under a code-sharing agreement, cancelled three flights between London and Madrid, and two connecting the capital with Barcelona. Some 240 Iberia flights are likely to be cancelled daily until Sunday, due to the strike action over feared job losses.

A BA spokesman said today: "We are working on contingency plans to ensure that as many British Airways customers who are booked on Iberia flights can get to their destinations.

"We would urge any BA customer who has booked a flight between Heathrow and Madrid or Barcelona on July 10, 11 and 12 to contact BA if they booked their ticket direct from the airline or their travel agent to see if their flight is affected and how they can be re-accommodated."

A statement on the British Airways website informed affected passengers that they could make changes to their booked journeys, obtain a refund or re-route with no penalty, regardless of fare type. New tickets would be valid for travel until the end of the year.

Birmingham Airport said that its flights to Barcelona and Madrid today were unaffected.