The anarchists' demonstration near the modern art museum Kiasma drew a few hundred participants. Police closed off the area and demanded information on the group's plan. The police, in riot gear, were met by a barrage of thrown bottle, stones and petrol.
At the start of the event, police has informed protesters that the demonstration would not be allowed to move out of the museum square. The decision was based on advance information that a degree of vandalism was to be expected.
Summit meetings and the start Sunday of the two day Europe-Asia ASEM meeting has brought a large number of protestors to the Finnish capital.
Saturday afternoon's demonstration by Helsinki 2006, a coalition of civic groups, drew around 1500 participants protesting neoliberalism and privatisation trends in the EU, among other social issues. It was carried out in a peaceful an orderly manner.
Police have maintained a high profile this weekend and, at least nine people were detained on Saturday in various incidents for vandalism or disorderly conduct.
A Saturday morning demonstration by supporters of the Falun Gong, a movement banned in China, was orderly and took place ahead of schedule by an understand reached by organizers with the Helsinki police.
There are special restrictions on traffic in central Helsinki because of the demonstrations and summit-related security measures.