Havoc in cities across Greece as protesters talk of 'social revolution'

Tear gas filled Syntagma Square outside Greece's parliament as police clashed with left-wing demonstrators, beating some with batons and detaining others.

Anger over the 15-year-old boy's killing has turned to resentment over economic hardships and could topple the unpopular conservative government.

"We are experiencing moments of a great social revolution," said Panagiotis Sotiris, 38, an activist among those occupying a university building.

"The protests will last as long as necessary."

Protests were reported in more than ten cities across the nation of 11 million people, including the northern city of Thessaloniki, and on the tourist islands of Crete and Corfu.

Youths appeared to be in control of central Athens, plundering and setting fire to shops, destroying banks and attacking ministries. The city's huge Christmas tree went up in flames.

"We are not counting any more. The incidents cannot be counted," a fire brigade officer said last night.

Firefighters extinguished a fire at one department store but the headquarters of Olympic Airways were still burning and all the city's fire engines were on the streets, he said.

More than 130 shops have been destroyed in the capital, crushing retailers' hopes that Christmas would compensate for Greece's darkening economic outlook. Police have detained more than 35 people and more than 50 are injured.

With a 24-hour general strike due tomorrow, in protest against economic reforms, analysts said Greece's worst riots in decades looked set to continue and could threaten the government, which has a one-seat parliamentary majority.

The socialists already held a strong lead in opinion polls before the riots, riding a wave of discontent at the ruling New Democracy Party's privatisations and pension reforms. Political analysts say an early election could be called next year.

Costas Karamanlis, the prime minister, expressed sorrow for the family of the dead boy, but warned demonstrators to stop.

The government would try to compensate property owners, he said.

As night fell on the Greek capital, thousands marched arm-in-arm through its main streets. Anarchists smashed car windows and chanted "cops, pigs, murderers". Some threw firebombs at police as businesses burned.

The shooting of Alexandros Grigoropoulos by a policeman on Saturday has kindled smouldering anger among Greek youths, resentful at a widening gap between rich and poor made worse by the global credit crisis.

Violence at student rallies and firebomb attacks by anarchists are common, especially in Athens' Exarchia district where the boy was shot. But anger at the boy's killing has even reached Greeks overseas, who protested in London and Berlin.

Five men were arrested in London yesterday for public order offences after they took part in a 40-strong protest outside the Greek embassy in Holland Park.

Two police officers have been charged over the shooting – one with murder and the other as an accomplice. A police statement said one officer fired three shots after their car was attacked by 30 youths in Exarchia.