Protesters hurled firebombs at riot police, who answered with teargas, as 4,000 Greek students marched yesterday in a sixth straight day of anti-government violence.

Riots across Greece, triggered by the police shooting of a teenager but fuelled by deep popular anger over corruption and economic hardship, have shaken the conservative government.

"Down with the government of murderers," read demonstrators' banners. Marchers chanted "Cops, Pigs, Murderers" in the latest spasm of Greece's worst unrest since the aftermath of its 1967-1974 military rule.

Helicopters hovered overhead as the protesters set fire to piles of garbage in the middle of deserted Athens avenues.The violence was less intense than in previous days, but more protests are planned for today and Monday and some Greeks asked how much longer the government could remain in power.

"The government has shown it cannot handle this. If police start imposing the law, everyone will say the military junta is back," said Yannis Kalaitzakis, 49, an electrician. "The government is stuck between a rock and a hard place."

Earlier in the day, gangs of Greek high school students hurled stones and firebombs at police stations in Athens suburbs. Violence has hit at least 10 cities and caused damage worth hundreds of millions of euros.

Data released on Thursday showed that economic hardship is hitting more Greeks. Unemployment, especially high among young people and women, rose to 7.4 per cent in September from 7.1 in August, reversing four years of decline, and economists said it would keep climbing as the global crisis reached Greece.

"Our priority is to help social groups that are most in need and protect jobs," Prime Minister Costas Karamanlis said in Brussels, where he is attending an EU summit.