Hundreds of people demonstrated in the centre of Athens and other cities early on Sunday, setting fire to a dozen cars, after a 15-year-old boy was shot dead by a policeman, police said.

The demonstrators, mostly residents of Athens' Exarchia district where the incident occurred, protested against the "arbitrary" police action, shouting slogans against the right-wing government of Prime Minister Costas Caramanlis.

The boy died on Saturday after a policeman fired into a crowd of youths who had lobbed molotov cocktails at a police car, police said. The boy was rushed to a nearby hospital where he was confirmed dead.

Youths set fire to garbage bins in the central Exarchia district, scene of frequent clashes with police, as news of the boy's death spread.

Protests later erupted in Salonika to the north and Patras to the south. The demonstrators targeted banks, damaging 17 in Athens and five in Salonika, the police said.

Interior Minister Prokopis Pavlopoulos and the police expressed "deep regret" over the shooting and ordered an inquiry headed by three prosecutors.

Pavlopoulos and junior minister Panayotis Hinofotis offered their resignations to the prime minister, who did not accept them.

In 1985, 15-year-old Michalis Kaltezas was shot by a police officer, triggering violent clashes between far-left youths and the police in Exarchia.

AFP