Outraged protesters in Spain, Denmark and Italy smashed shop windows, pelted police with bottles and attacked banks, in an alarming indication that the unrest that has gripped Greece for most of the past week could spill over into the rest of Europe.

In France, cars and a garbage can were set alight outside the Greek Consulate in Bordeaux yesterday, and protesters scrawled graffiti warning of a looming “insurrection.” More demonstrations had been set for today in Italy, France and Germany.

At least some of the protests appear to have been organized over the Internet, showing how quickly a message can be spread, particularly among tech-savvy youth.

Several Greek websites offer protesters real-time information on the location of clashes, where demonstrators are heading and how riot police are deployed around the city. Protest marches are arranged and announced on the sites, while word is also sent out via text messages on mobile phones.

In Spain, an anti-globalization website, Nodo50.org, greeted visitors with the headline “State Assassin, Police Executioners,” telling them of the hastily organized rallies in Barcelona and Madrid on Wednesday.

Elsewhere, reports about the protests and riots in Greece were quickly picked up online by citizen journalists, some of whom detailed seeing confrontations on Twitter. At the Independent Media Center, photos and videos of the demonstrations were uploaded and plans were listed for “upcoming solidarity actions” in London, Edinburgh and Berlin.

“What’s happening in Greece tends to prove that the extreme left exists, contrary to the doubts of some over these past few weeks,” French Interior Ministry spokesman Gerard Gachet told The Associated Press. “For the moment, we can’t go further with our conclusions and say that there’s a danger of the Greek situation catching on in France.”

In Italy, a group of protesters gathered in front of the Greek Embassy in Rome on Wednesday and some turned violent, damaging police vehicles, overturning a car and setting a trash can on fire.

In Denmark, protesters pelted riot police with bottles and paint in downtown Copenhagen at a rally late Wednesday. Some 63 people were detained and later released.

In France, protesters set fire to two cars and a garbage can apparently stuffed with flammable material outside the Greek Consulate in Bordeaux early yesterday and scrawled graffiti on the building threatening more unrest, Michel Corfias, the Greek consul, told The Associated Press. (AP)