Greek police clash with youths over 2008 shooting

A riot policeman tries to avoid flames from a molotov cocktail thrown by a protester after a rally marking the 2008 shooting of a student by police in Athens December 6, 2012.

ATHENS (Reuters) - Greek police fired tear gas at youths hurling petrol bombs and stones in Athens on Thursday after a peaceful march to mark the 2008 police killing of a teenager that sparked the country's worst riots in decades.

Hundreds of students, teachers and leftists held rallies in the capital and other major cities throughout the day, chanting "Cops, pigs, murderers!" and "These are Alexis's days!" in reference to 15-year-old Alexandros Grigoropoulos.

Clashes erupted in the evening after dozens of hooded youths broke off from a 1,000-strong march, throwing petrol bombs and stones at riot police in the Exarchia neighborhood where Grigoropoulos was shot.

Six cars were set alight and at least 28 people were detained, police said.

Thousands of people took to the streets of the capital just hours after the shooting on December 6 2008, torching cars and smashing shop windows.

Fuelled by anger at unemployment and economic hardship, the riots lasted for weeks, turning central Athens into a virtual no-go area and helping topple the conservative government of Costas Karamanlis.

(Reporting by John Kolesidis; Writing by Karolina Tagaris; Editing by Andrew Roche)