About 150 anti-globalisation protesters attacked the Italian and Canadian embassies in London overnight, smashing windows and damaging a car.
The protests were dispersed after about three hours last night, a police spokesman said. Three men in their twenties were arrested.
The protest, which began outside the Italian embassy, was in response to the killing of an anti-globalisation demonstrator by Italian police at the Group of Eight summit in Genoa, the spokesman said.
"A small number of missiles were thrown by the group, causing minor damage to a building near the Italian embassy," he said.
The group then moved toward the Canadian embassy where windows were smashed and damage to a car was reported.
The next G8 summit will be held in the Canadian Rockies.