Iberia said it has found alternative flights for about 38,000 of the 40,000 passengers booked on flights cancelled by the second in a series of three week-long strikes by the airline’s ground staff and cabin crews that began Monday and will last all week.

The airline said it would offer new travel dates or full refunds to the 2,000 passengers it was unable to accommodate.

Iberia said it was cancelling 431 flights this week—about 39% of its usual flight schedule—because of the strike, but would operate 680 flights—the remaining 61%. The airline said that it would operate 85% of all scheduled long-haul flights and 62% of medium-haul international flights, as well as 47% of domestic flights.

The strike is threatening to spill over to British Airways (BA), which is also owned by Iberia parent International Airlines Group (IAG). BA members of the Unite union in the UK are planning to stage a demonstration outside IAG offices on Wednesday. Unite is the UK’s largest trade union and represents personnel across British Airways.

Unite general secretary Len McLuskey said, “If [IAG CEO] Willie Walsh thinks British Airways staff will keep quiet while he attacks their colleagues in Iberia, he is wrong. We all support those threatened by Walsh’s reckless plans.”

The British Airline Pilots’ Association (BALPA) has weighed into the debate in support of the Spanish Pilots’ Association, Sepla, which stayed out of the earlier strike, but has joined this week’s industrial action.

A further five days of strikes are planned for March 18-22, with unions reportedly threatening to extend action over the Easter peak.