Greece plunged into chaos as rioting entered its fourth day on Tuesday with hundreds of protestors hurling stones and bottles at police in front of the Greek parliament.
The conservative government was looking increasingly fragile as socialist opposition leader George Papandreou called for new elections to stop the crisis.
Tuesday's protests came hours before the funeral of a 15-year-old youth whose killing by a policeman on Saturday triggered Greece's worst riots in a quarter of a century.
Hundreds of buildings have been wrecked or burned and more than 50 people injured.
Prime Minister Costas Karamanlis, speaking after a meeting with political leaders including Papandreou on Tuesday, said the protestors could expect no leniency.
Police Prepare for Worst
"No one has the right to use this tragic incident as an excuse for acts of violence," said Karamanlis, whose government is clinging to a slender majority.
Police are bracing for more trouble in Athens later on Tuesday when Alexandros Grigoropoulos—the youth who was shot dead—is buried. His shooting acted as a trigger for protestors to vent their resentment over the government's economic policies, corruption scandals, and growing inequality.
Two police officers have been charged in the shooting—one with manslaughter and the other as an accomplice. A police statement said one officer fired warning shots after his car was attacked by 30 youths in Athens' volatile Exarchia district. But witnesses speaking to Greek TV accused him of taking aim at the teenager.
One of the police officer's defense lawyers resigned on Monday, saying his conscience forbade him from defending "such a client." Greek radio reported that the officer who fired the shot was known as "Rambo" because he was prone to take tough action.
Since Saturday, protests have been reported in more than 10 cities across the nation of 11 million people, including the northern city of Thessaloniki and the tourist islands of Crete and Corfu.
Youths appeared to be in control of central Athens for several hours on Monday night, looting and setting fire to shops, destroying banks and attacking ministries. Even the city's huge Christmas tree was set ablaze.
More than 130 shops have already been destroyed in the capital, dashing hopes of brisk Christmas trading in the face of a worsening economic outlook.
Police have detained more than 35 people and more than 50 have been injured in the rioting since Saturday.
"We are experiencing moments of a great social revolution," leftist activist Panagiotis Sotiris, 38, among those occupying a university building, told the Reuters news agency. "The protests will last as long as necessary."
Around 100 stores were plundered in the northern city of Thessaloniki on Monday night. The rioters smashed shop windows and stole watches, jewellery and clothing, AFP reported.
A police station was attacked by around 20 youths hurling firebombs. A total of 5,000 people took part in two separate demonstrations in Thessaloniki.
Protestors occupied the Greek consulate in Paris on Tuesday following a similar action in Berlin on Monday. There have also been demonstrations at the Greek embassies in London and Nicosia, Cyprus.