Spain temporarily restored border checks in its northeast and at two major airports early Saturday in a bid to discourage protesters entering the country ahead of a European Central Bank meeting in Barcelona.
The Catalan regional capital is to host an ECB governing council assembly on May 3 as the financial crisis in Spain deepens, with 24.4 percent of the work force unemployed and the economy lurching into its second recession in three years.
Spanish authorities suspended the Schengen Treaty, which allows unrestricted travel inside member nations, and imposed controls at six border crossings with France and at Barcelona and Gerona international airports.
Security forces have been strengthened with 2,000 extra police on duty until midnight on May 4, when the restrictions are due to end.
At the La Jonquera border crossing in the foothills of the Pyrenees Mountains, around 50 police reinforced normal border guards and randomly stopped vehicles to ask for identity and vehicle documents.
The office of Prime Minister Mariano Rajoy said on its official website that the text of the Schengen agreement states that free movement of people in borderless Europe can be stopped temporarily "if a serious threat to public order or domestic security exists."
Rajoy's government has approved a number of stinging austerity measures in its five months in office with the aim of staving off a need to seek a bailout like Greece, Ireland and Portugal.
Those spending cuts, tax hikes and fiscal reforms, combined with around 50 percent of young people unable to find work, have sparked street protests.
During a general strike in late March some youths threw bricks and burned garbage bins in central Barcelona. Police confronted and dispersed the rioters with baton charges and by firing rubber bullets.
Deputy Prime Minister Soraya Saenz de Santamaria said the government was prepared to take tough measures to ensure that violent demonstrators did not hamper other people's right to peaceful protest.
Associated Press writer Harold Heckle in Madrid contributed to this story.