ATHENS, Greece - Masked youths set up burning barricades and threw firebombs and rocks at riot police yesterday, after a protest march erupted into new fighting that sent Christmas shoppers fleeing to safety.

Mothers snatched children from a carousel in the main square. Waiters stumbled from cafes choking on tear gas fired by police at rioters trying to burn the capital's Christmas tree, replaced just days ago after another tree was torched.

After two weeks of rioting set off by the fatal police shooting of a teenager, a slogan spray-painted outside the Bank of Greece caught the mood as Greeks prepared for Christmas: "Merry crisis and a happy new fear."

But protesters' call for European-wide demonstrations of support - urged in banners defiantly unfurled from the ancient Acropolis on Wednesday - met with no apparent response.

Yesterday's clashes broke out in front of Parliament at Syntagma Square during a demonstration against police brutality. *