Police in Rome have arrested about 40 people protesting against this week's G8 summit.
Officials and witnesses say demonstrators hurled bottles and set tyres alight on the streets of the city, on Tuesday.
The demonstration reportedly started peacefully but turned sour outside the University of Rome, when protesters, some masked or hooded, threw bottles and stones at police vehicles.
About 15,000 police have been mobilised to provide security during the three-day G8 summit in L'Aquila, the city devastated by an earthquake in April.
The summit runs from Wednesday to Friday