Clashes between Greek youths and police in Athens continued well into the night Saturday, dashing hopes that two weeks of rioting would subside as Christmas neared.
Hundreds of people gathered for a memorial in Exarchia district near the capital city's center where police fatally shot a teenager, Alexandros Grigoropoulos, two weeks ago.
Protesters set fire to more buildings and cars and hurled firebombs at police who responded with tear gas.
Earlier in the day, rioters attacked a Christmas tree in the central Syntagma Square with garbage. The square's first Christmas tree was burned to the ground days after the shooting of the teenager.
In the northern city of Salonika, protesters occupied a movie theater in the city's main square and pelted the mayor with pastries.
Rage over the killing set off Greece's worst unrest in decades and turned into anger over corruption and economic hardship.
Greek media describe the protesters as self-styled anarchists and youths belonging to far-left militant groups.
Prime Minister Costas Karamanlis says the protests have damaged the country's economy, with retailers reporting more than a billion dollars in damages and lost sales.
Meanwhile, protests are spreading beyond Greece's borders. In the northern German city of Hamburg, about one thousand demonstrators marched through the streets Saturday in support of the Greek protests.
Local officials said protesters threw bottles, iron bars and fireworks at police who arrested several people.
Some information for this report was provided by AFP and AP.