The first day of a strike by employees of Spanish airline Iberia to protest a restructuring plan that includes 3,807 layoffs led to the arrest of five people at Madrid's Barajas International Airport.

Unions representing ground staff and cabin crew have announced plans for strikes on 15 days against a plan that envisions the elimination of 19 percent of Iberia's workforce in the course of this year.

Some 8,000 Iberia workers gathered at Barajas, but what was intended to be a demonstration outside Terminal 4 quickly became a takeover inside the facility after protesters broke through the police cordon.

Workers occupied the terminal with a sit-in during which they chanted slogans like "the dismantling of Iberia" and also against "English piracy," a reference to the 2011 merger of the Spanish company with British Airways.

For three hours there were verbal clashes and several scuffles with the more than 300 police deployed at the scene, leaving one person injured and five others in custody.

Iberia announced that more than 1,200 flights will be grounded this week due to the strike.

A total of 415, or 39 percent, of Iberia's 1,062 scheduled flights are to be grounded, while its subsidiaries - Vueling, Air Nostrum and Iberia Express - will cancel a combined total of more than 800 flights due to a loss of ground assistance normally provided by the Iberia Airport Services division. EFE