Police and protestors clashed Saturday at a demonstration against plans for the expansion of a US military base in Vicenza in northern Italy, local media reports said, according to dpa. Protestors pelted threw stones at riot police, who responded with tear gas and batons, according to the reports. Several thousand people took part in the demonstration, dozens of them wearing masks. The protest that came four days before Italy hosts the annual summit of the Group of Eight (G8) industrialised nations in the city of L'Aquila, was seen by some as a dress rehearsal.