Naples' mayor appealed to residents Saturday to stay calm over stinking mountains of trash in the city that have gone uncollected for more than two weeks.
Groups of youths, with their faces largely covered, threw stones and other objects at riot police before dashing away, some of them on motor scooters, news agency Apcom reported.
In the Pianura neighborhood, the heart of the protests, residents tossed tree trunks on roads and spread oil on streets to try to thwart the arrival of police.
Residents have also taken to burning trash, unleashing clouds of smoke in the city.
Refuse uncollected since Dec. 21
Mayor Rosa Russo Iervolino said she was appealing to the "overwhelming majority" of law-abiding citizens in the Pianura neighborhood, where work has begun to reopen a long-closed dump.
"Respect the law," the mayor was quoted as saying by the ANSA news agency.
She also said she sympathized with residents because garbage collectors have not been picking up trash since Dec. 21. There is no more room for it at dumps.
Officials have blamed organized crime's infiltration of garbage collection services and disorganized bureaucracy for the piles of trash on the city's outskirts and lining streets in Naples' historic center.
Trash crisis alarms Italian president
President Giorgio Napolitano has said he was "alarmed" by the situation and called on officials to make sure the situation is resolved.
Garbage pileups because of shortage of space in dumps have plagued the port city sporadically for several years. Although citizens are angered by the mountains of trash, they have also blocked plans to open new dumps in the Naples area.
Premier Romano Prodi told journalists in his hometown of Bologna that Naples' garbage problems needed to be solved "once and for all." He said government ministers would meet Monday to come up with a strategy.
"Everybody's watching us, and I don't want Italy to give off this negative image," Prodi said. "It's an emergency we must tackle rapidly."