ATHENS, Greece (AP) -- Protesters hung giant banners off the Acropolis Wednesday calling for mass demonstrations across Europe, heaping embarrassment on a government reeling from Greece's worst riots in decades sparked by the police shooting of a teenager.
The two pink banners were unfurled over the walls of the ancient citadel that towers above central Athens and could be seen for miles around. One bore the word "Resistance" in large black letters in Greek, English, Spanish and German.
The other called for demonstrations throughout the continent Thursday, when students plan major marches in Athens and Greece's second largest city of Thessaloniki to protest the death of 15-year-old Alexandros Grigoropoulos, killed in a police shooting on Dec. 6.
The government was furious at the use of Greece's most famous monument.
"There can be no justification for this action," government spokesman Evangelos Antonaros said. "This hurts the image of our country abroad ... it is unacceptable."
Although sparked by Grigoropoulos' death, the riots were fed by dissatisfaction with the increasingly unpopular conservative government and widespread anger over social inequality and economic hardship.
The violence spread quickly across the country with masked and hooded youths fighting with riot police night after night. The violence left hundreds of shops and bank branches smashed, burned and looted and dozens of cars torched. Retailers say the damage will cost them euro1.5 billion ($2 billion) in lost income.
Prime Minister Costas Karamanlis has rejected opposition calls for early elections, saying the country needs a steady hand to deal with the international financial crisis.
There has been concern that the unrest could spill over Greece's borders, with shows of support in several European countries, including Spain, France and Germany. German police say a solidarity protest is planned for Thursday in Berlin and is expected to be attended by about 500 people.
After more than a week of violence, Greece's mainly young protesters have begun changing tactics to attention-grabbing stunts.
The banners came a day after a group of youths forced their way into Greece's state television studios, disrupting a news broadcast of a speech by Karamanlis.
The youths appeared live on national television behind black banners that read: "Stop watching, get out onto the streets" and "Free everyone who has been arrested." In Thessaloniki, protesters broke into three local radio stations, agreeing to leave only when a protest message was read on the air.
More than 300 people have been arrested since the riots started, and the main courthouse in Athens has been the scene of tense confrontations between riot police and angry students demanding the release of those detained during the unrest.
About 100 high school students gathered outside the court complex Wednesday, pelting riot police with stones, eggs, rocks and yogurt. No injuries were reported.
Later in the day, about 2,000 protesters marched peacefully through the center of the capital to protest against labor reforms and the police.
Although the rioting has abated, small-scale attacks continue. Police said about a dozen youths on motorcycles set fire to a police bus in central Athens. The driver managed to escape the fire and no one was hurt.
Also Wednesday, about 40 protesters occupied the offices of the Greece's largest labor union, the GSEE.
"I believe they have chosen the wrong target ... The GSEE does not govern this country. So it's wrong to undermine the labor unions," GSEE leader Yiannis Panagopoulos said.
Further disruption is expected Thursday with industrial action by air traffic controllers halting all flights for three hours at Athens International Airport.
Associated Press writer Matt Moore in Berlin contributed to this report.