Thousands of rioters across Greece have clashed with police in a third day of violent protests over the fatal shooting of a 15-year-old boy.

Police used teargas against protesters roaming the streets of Athens throwing petrol bombs and setting fire to buildings, vehicles and rubbish bins.

Dozens of people have been injured throughout the country and there are reports of looting in some areas.

Prime Minister Costas Karamanlis has gone on television to appeal for calm.

He said "extreme elements" were taking advantage of the situation to engage in vandalism and pledged to compensate businesses damaged.