Protesting youths rioted in central Athens for more than six hours Monday, attacking police with rocks, flares and petrol bombs, after a student rally marking two years since the fatal police shooting of a teenage boy.
The boy's death in 2008 sparked Greece's worst riots in decades, led to an surge in attacks by militant groups and continued anti-government violence as the country grapples with a serious debt crisis.
On Monday, police detained 83 youths in Athens, and five people were hurt, including a bystander hit in forehead by a flying rock.
The clashes stretched from parliament to the site where 15-year-old Alexandros Grigoropoulos was shot, about a mile (1.5 kilometers) away, where several hundred people gathered late Monday, leaving flowers and candles.
Earlier, some 4,000 people marched to parliament where they confronted police who had closed much of the city to traffic.
The youths smashed several store fronts, glass phone booths and other property. Riot police responded with tear gas and pepper spray as the masked youths used smashed-up paving stones and ripped-up traffic signs to throw at them, and set fire to trash bins to use as barricades, outside parliament and the city's main Syntagma Square.
Several bank and other store fronts were smashed, but the damage was not extensive.
Despite the choking atmosphere from the tear gas, much of the city continued as normal. Some large stores remained open but shuttered their main entrance, allowing customers to continue Christmas shopping while protesters rampaged outside.
"Today marks two years since the tragic death of young Alexandros Grigoropoulos. Today we honor his memory," government spokesman Giorgos Petalotis said. "Those who honor him should not resort to violence."
The 2008 riots was the worst civil unrest in Greece in recent memory, with youths rampaging through cities almost nightly for two weeks.
The trouble also inspired a wave of violence by far-left and anarchist militant groups, reviving decades-old antiestablishment violence rooted in past political upheavals.
Over the weekend, police arrested six suspected members of a militant group and seized explosives and weapons from suspected safe houses. Police ballistics tests have not matched any of the seized weapons to previous terrorist attacks.
On Monday, police closed main roads to traffic around Athens and deployed several thousand officers in the capital. About 2,000 people also attended a protest rally in the country's second largest city, Thessaloniki.
A court in October convicted policeman Epaminondas Korkoneas of murder for the teenager's death, and sentenced him to life imprisonment. A second officer was jailed for 10 years.
The dead teenager's mother said she was planning to set up a foundation to assist victims of mistreatment by the authorities.
"They shot my son in cold blood. He was hit in the heart and died instantly," Gina Tsalikian told state-run NET television in an interview aired late Monday.
"I wish that no other mother goes through what I have been through."
AP writer Derek Gatopoulos, AP photographer Thanassis Stavrakis and AP television producer Theodora Tongas contributed.