***UPDATE*** 6:25PM Fox News reports that rioters in Greece are using lasers to combat police:
A gang of masked protesters attacked the Greek riot police headquarters Tuesday amid reports that rioters are using lasers to combat police officers.
Authorities trying to contain the gangs of rioters were hit with blinding flashes of green light as the violence in Greece entered a second week, the U.K.'s Daily Mail newspaper reported.
The riot police headquarters in Athens was damaged, but no officers were injured.
From AP: Greek protesters pushed their way into television and radio studios Tuesday, forcing broadcasters to put out anti-government messages in a change of tactics after days of violent street protests.
A group of about 10 youths got into the studio of NET state television and turned off a broadcast of a speech by Prime Minister Costas Karamanlis, station officials said. The protesters forced studio cameras to instead show them holding up banners that read: "Stop watching, get out onto the streets," and "Free everyone who has been arrested." No one was hurt, and no arrests were reported.
NET chairman Christos Panagopoulos said the protesters appeared to know how to operate cameras and studio controls.
"This goes beyond any limit," he said.
In the northern city of Thessaloniki, protesters made their way into three local radio stations, agreeing to leave only when a protest message was read out on the air.
Violence also broke out again after a two-day lull as masked youths attacked riot police headquarters in Athens and protesters clashed with police in Thessaloniki.
Police said 30 youths threw petrol bombs and stones at the riot police building, damaging seven cars and a police bus parked outside.
In Thessaloniki, riot police fired tear gas to disperse 300 youths throwing fruit and stones outside the city's main court complex. The disturbance followed a court decision that found eight police officers guilty of abusing a student following riots two years ago.
Overnight, arsonists attacked three Athens banks with petrol bombs, causing extensive damage.
The fatal police shooting of 15-year-old Alexandros Grigoropoulos on Dec. 6 set off violence that led to more than 300 arrested and left hundreds of stores smashed and looted. Retailers say the damage will cost them euro1.5 billion ($2 billion) in lost income.
Protesters have called for riot officers to be pulled off the streets and for police to be disarmed. But the protests tapped into wider discontent with Karamanlis' conservative government and there have been widespread calls for the government to revise its economic, social and education policies.
Higher education in Greece has come to a standstill. Lessons have stopped at more than 100 secondary schools that are under occupation by students, according to the Education Ministry. Scores of university buildings across Greece are also occupied.
Greece's opposition Socialists, who are calling for early elections, accused Karamanlis of mishandling the crisis which they said had worsened the effects of the international economic downturn.
"Greeks are losing their patience. Their salary is running out before the end of the month as they endure a major economic crisis, and at the same time can see the state collapsing," Socialist spokesman Giorgos Papaconstantinou said.
"People want answers to their problems, not speeches."
Karamanlis insisted his government has acted "calmly and responsibly" in dealing with riots, avoiding the loss of life. But for the first time since the violence erupted, he acknowledged the public's sense of frustration.
"Of course there are broader issues," he said. "People experience a lack or merit, corruption in their daily lives, and a sense of social injustice."
In Athens main Syntagma Square, Mayor Nikitas Kaklamanis relaunched holiday celebrations after the city's Christmas tree was torched by rioters last week.
A small group of protesters chanted slogans during tree-lighting ceremony, as hundreds of revelers looked on. The protesters, mostly students from various drama schools, handed out fliers that read: "Lavish storefront and Christmas Trees will not hide the reality."
Associated Press writers Nicholas Paphitis, Costas Kantouris and Elena Becatoros and AP photographers contributed to this report.