BERILN, Sept. 18 (Xinhua) -- German police searched premises in Hamburg, Schleswig-Holstein and North Rhine-Westphalia on Tuesday in connection to the widely-publicized riots during the Hamburg G20 summit last year.

A police spokesperson confirmed the development, as well as a "BILD" report that a 35-year-old German had hereby been arrested in the Winterhude quarter of Hamburg. No information was provided with regards to the charges filed by prosecutors against the suspect.

The focus of the ongoing operation is placed on individuals who are suspected of having broken the law at a "Welcome to Hell" demonstration which left a trail of destruction in the Elbchaussee area of the northern German city. Amongst others, alleged offenses under investigation by state prosecutors and police include disturbing the public peace and resisting and using violence against security officers.

A special investigatory commission "Schwarzer Block" (literally black block, the German name of a radical subgroup of demonstrators) has been established in Germany towards this end. It is being supported by a multinational police force, as well as the European Union's (EU) Eurojust agency in Den Haag. Back in May, the German Federal Criminal Police Office (BKA) already launched a joint investigation into 24 key suspects with security forces in 15 European countries.

Hamburg's state interior minister Andy Grote (SPD) has likened some incidents of rioting during the G20 summit in the city to terrorism. "This was a concerted criminal operation which approaches the patterns which we would usually describe as terrorist", Grote said. The SPD politician highlighted that some left-wing extremists had demonstrated a willingness to put human lives at risk in the escalating demonstrations.

According to Jan Hieber, director of the "Schwarzer Block" special investigatory commission, around 220 individuals clad in paramilitary gear succeeded in causing 1.5 million euros (1.75 million U.S. dollars) of damage in only 19 minutes during the most notorious of the riots in the Elbchaussee part of Hamburg. The group set cars on fire and attacked police vehicles as well, leading one security officer to draw his weapon. "It could have easily ended with fatalities", Hieber said.

On Tuesday, German police launched a further European investigation into four suspects, three men and one woman, who are believed to have be responsible for a series of arson incidents. Hamburg police published images of the individuals on their website with a call for members of the public to come forward with any information they may have about their whereabouts.