Demonstrators holding a march and rally to oppose next week's G8 summit clashed with police in the northern German port of Rostock Saturday, overturning cars and throwing stones and petrol bombs, DPA reported. Two police officers were injured, police said, while eyewitnesses said at least one demonstrator was also hurt as the violence escalated by mid-afternoon. Police and anti-globalization demonstrators faced each other across a major road near the harbour, where the protest was to culminate in a rally. The demonstrators were urged to resist the police over a loudhailer. Eyewitnesses said police had brought in reinforcements, including a water cannon and riot vehicles. Two helicopters circled overhead. A spokesman for the protest organizers accused police of provoking the violence. Earlier police reported that a dozen people, their faces covered to prevent identification, had attacked a police car near the harbour. They said that fewer than 30,000 anti-globalization protestors were taking part, well down from the 100,000 expected by the organizers in the largest rally planned ahead of the summit. Many of the demonstrators, who include peace activists and environmentalists, arrived at two main gathering points on special trains or by bus, while others had camped near the city overnight. The protest, under the slogan, "Another world is possible," was being held to oppose the G8 summit being held from Wednesday to Friday in the resort of Heiligendamm some 25 kilometres away. In the city itself, shopkeepers and traders had battened down the hatches, protecting display windows with wooden boards.