By Catherine MacDonald and Sarah Morris
MADRID (Reuters) - Striking union workers clashed with police at Madrid's Barajas airport on Monday on the first day of a week-long strike over more than 3,800 pending job cuts at Spain's flagship airline Iberia.
More than 80 Iberia flights were canceled as workers at the carrier began a series of five-day walkouts that are expected to cost the airline and struggling national economy millions of euros in lost business.
Hundreds of workers flooded into Terminal 4 at Barajas - the biggest airport in Spain - to noisily protest, chanting and whistling, with one group staging a sit-in. About 2,000 people demonstrated outside the terminal.
The police beat some strikers with truncheons to keep them away from the doors of the international airport, Iberia's Madrid hub, and forcefully threw others out of the terminal. At least five protesters were arrested.
Previous strikes have cost Iberia between 2 million euros and 3 million euros a day, a spokesman told Reuters.
Flights from other airlines were delayed at airports across Spain, including at Madrid and Barcelona, as Iberia baggage handlers, also working for other airlines, joined strikers.
Air stewards and ground staff are holding three five-day strikes in February and March to protest against management plans to axe jobs and cut salaries at the loss-making airline. Some 10 percent of long-haul flights and half of domestic flights will be grounded this week.
Labor unions kicked off the strikes with demonstrations in the morning at most Spanish airports, including Barcelona. At an 8 km march (5 miles) around Barajas, protesters blamed British managers at the airline group for job cuts threatened in Spain.
Demonstrators waved Spanish flags and banners saying "British go home".
Iberia, which merged with profitable British Airways in 2011 to form the International Airlines Group (IAG), reported a loss of 262 million euros ($349.78 million) in the first nine months of 2012.
"Nobody is safe from being sacked," said Elias Gonzalez, a maintenance supervisor at the Barajas protest who has worked for Iberia for 27 years.
"There was an initial deal with the company when the merger with the British was agreed, but now there is disagreement."
Although skeleton staff were on duty and the airline had rescheduled most passengers or returned them their money, some people were left stranded.
"When we come for tourism, we don't want to be bothered by strikes," said Robert, a French tourist who did not want to give his last name.
"Everyone has their problems but they shouldn't bother people who bring in money. That's also business."
Queues formed as some staff abandoned check-in desks while unionists shouted in the airport.
The February 18-22 strike coincides with school holidays in Britain and France, Spain's biggest source of tourists.
Tourism accounts for around 11 percent of Spanish economic output and is one of the country's few growth sectors in a prolonged recession that has pushed the unemployment rate above 26 percent.
In anticipation of the strike, Iberia has canceled 415 flights between Monday and Friday, and as many as 1,200 flights operated by various airlines will be disrupted because some Iberia workers handle baggage for other airlines at airports around Spain.
Some 70,000 passengers will be affected. About 86 percent have been given a different flight, including those operated by other airlines, while 14 percent have asked for refunds.
The airline says restructuring is vital to return the Spanish unit to profitability while unions say the IAG management is degrading pay and benefits in Spain through its new low-cost airline Iberia Express.
Iberia is just one of several companies in Spain, including Vodafone and bailed-out lender Bankia, to lay off workers.
It is fighting an uphill battle against low-cost operators, a depressed domestic economy and competitors which are in better shape after having already gone through restructuring processes.
Sabadell Bolsa analysts said the total 15 days of strikes could cost Iberia between 50 million euros and 100 million euros of losses. ($1 = 0.7490 euros)
(Additional reporting by Robert Hetz and Silvio Castellanos in Madrid and Ayla Jean Yackley in Barcelona; Writing by Clare Kane and Sarah Morris; Editing by Pravin Char)