TIMELINE: Emergency talks in Greece to stem riots

(Reuters) - Hundreds of protesters threw stones and bottles at lines of riot police outside the Greek parliament on Tuesday, in a fourth day of anti-government clashes triggered by police killing a teenage boy.

Here is a timeline of events.

December 6:

-- A police officer shoots dead 15-year-old Alexandros Grigoropoulos in central Athens. The policeman says he fired warning shots but witnesses say he aimed at the boy after a verbal altercation with some youths in the Exarchia district.

-- Thousands protest in Athens hours later, throwing petrol bombs, smashing shop windows and setting fires. Police clash with rioters using teargas, choking the capital's center.

-- Riots spread across Greece, to the northern cities of Thessaloniki, Komotini and Ioannina as well as the tourist resorts of Crete and Corfu. Police arrest six people for looting smashed shops and one is held for gun possession.

-- Interior Minister Prokopis Pavlopoulos makes a public apology and later submits his resignation, which is rejected by Prime Minister Costas Karamanlis.

-- Riots sweep across Greece through the night and two police officers are arrested over the teenager's death.

December 7:

-- Thousands of demonstrators chanting "Killers in Uniform" march for a second day in Athens, Thessaloniki, Crete, Patras, Corfu and Ioannina.

-- Prime Minister Costas Karamanlis sends a letter to the dead teenager's family, expressing his sorrow and promising the culprits will be punished. Pavlopoulos appeals for calm.

-- One police officer is charged with murder and another with abetting him.

-- Protesters in Athens and Thessaloniki clash with police and hurl fire bombs along the cities' main streets setting shops, buildings and cars alight.

-- The mayor of Athens postpones the launch of Christmas festivities.

December 8:

-- Demonstrators launch a third day of protests and occupy university buildings. Dozens of marches bring Athens to a standstill as shop owners count the damage. More than 130 shops have been destroyed in the capital.