ATHENS - The Greek capital was suffocating under a barrage of tear gas Thursday as 5,000 protesters swamped riot police outside parliament, 12 days after the police killing of a teenager sparked riots.
Militant youths tried to breach a cordon guarding the Syntagma Square complex, prompting police to use teargas, an AFP correspondent said.
Later, they attacked the city's giant Christmas tree on the square -- which had only been replaced on Tuesday after the first went up in flames on December 8, the third day of rioting and looting.
Greek authorities had earlier this week sent out urgent appeals to foreign countries for fresh stocks of tear gas -- and warned the public to steer clear of the city centre after a coalition of students, teachers, unions and left-wing demonstrators vowed to step up anti-government sentiment.
When the initial attack at the parliament was repelled, protesters came back with a hail of oranges -- before setting cars, bins and pavement cafe furniture ablaze as they retreated towards their rallying point, the Athens Polytechnic university.
Firefighters descended on the student quarter as youths hurled rocks at police -- while a stone's throw away, Athenians tried to do their Christmas shopping.
The bid to burn the Christmas tree was blocked by police, but youths later climbed the giant fir to shower the scene with pamphlets.
More rallies were planned for after dark.
Triggered by the fatal police shooting of 15-year-old Alexis Grigoropoulos, the unrest intensified after the 16-year-old son of a leading official in the Greek Teachers Federation -- which backs demonstrations across Greece -- was wounded in a rifle attack overnight in an Athens suburb.
Hit in the hand as he talked with other students, police said he spent the night in hospital before undergoing an operation.
Police said none of their officers were in the area at the time of the incident, but the Greek government promised a detailed inquiry.
Protest organisers had called for backing from across Europe, but the only reported rally by late afternoon was in Germany, where about 100 people marched in Berlin.
"We want to show that the movement in Greece isn't just about youths on the rampage but is a political movement," said Sofia Bemteza, 29, a Greek artist based there.
Police had cleared streets around the key Athens flashpoints and told residents not to venture out.
At the main rally, banners read "Mourning Is Not Enough, The Struggle Goes On."
Strikes and protests organised by a public employees' union over the Greek budget and anti-racism demonstrations -- which started Thursday as evening fell -- added to the turmoil.
Activists on Wednesday hung banners along the Acropolis monument and interrupted a state television broadcast in a bid to prolong their movement.
Meanwhile, a ballistics report on the death of Grigoropoulos was handed over to an investigating judge on Thursday.
The judge summoned lawyers for the police officer charged over the killing and the victim's family to inform them of the report's conclusions, a court source said.
Preliminary conclusions by medical examiners and experts working for the victim's family indicated damage to the bullet, suggesting it had touched a hard surface before hitting Grigoropoulos in the chest.
The officer, Epaminondas Korkoneas, 37, says he killed the boy by accident. His partner, Vassilios Saraliotis, 31, was charged with being an accomplice.