BERLIN, May 10 (Xinhua) -- Four people were injured and 12 taken into custody Wednesday evening in Berlin and Hamburg during demonstrations against police who raided buildings of militant groups plotting an attack on the Group of Eight (G8) summit in June, police said Thursday.

    Over 5,000 people protested in Hamburg, Berlin and other cities,police said.

    Clashes broke out in Hamburg, where police used water canons to disperse around 2,000 protestors. Some protestors threw stones and bottles at the officers.

    Four people were wounded and eight arrested during the two hours before calm was restored, according to the police.

    Over 3,000 people marched peacefully in Berlin, but four were arrested on the fringe of the demonstration.

    The protests came after around 900 police and prosecutors searched 40 premises in Berlin, Brandenburg, Hamburg, Bremen, Schleswig-Holstein and Lower Saxony for terror suspects planning to attack the June 6-8 G8 summit.

    According to the office of the Federal Chief Prosecutor, 18 people have so far been identified in one group, which had claimed responsibility under different names for 15 bombings or other vandalism in Hamburg and Berlin.

    The G8 summit will attract heads of government from Canada, France, Germany, Italy, Japan, Russia, Britain and the United States.

    Other countries that will join the talks include China, Brazil,India, Mexico and South Africa.