Interior Minister Alexander Dobrindt told Sunday's edition of Bild newspaper that he would step up action against left-wing extremists after the attack on Berlin's power grid, including with a package of tougher surveillance measures, reported dpa. "We are striking back, and we will not leave the field to left-wing extremists and climate extremists," the conservative politician told the newspaper. Security is a top priority, he said. He said the package of measures he envisages calls for not only more staff for the intelligence services but above all an expansion of digital powers to shed more light on the scene and to track digital traces more quickly. No specific numbers or details were provided. Some 100,000 people in south-west Berlin were left without power in the middle of winter with sub-freezing temperatures last week when a large-scale power outage followed an arson attack on a cable bridge. A far-left extremist organization, the Volcano Groups, claimed responsibility. They are believed to have repeatedly carried out arson attacks on public infrastructure mainly in Berlin and Brandenburg since 2011. The Federal Public Prosecutor's Office in Karlsruhe has taken over the investigation. Many worried about future attacks "What happened in Berlin could happen anywhere else at any time – in Cologne, Stuttgart or Munich. The state must not allow itself to be made to look so foolish," the chairman of the civil servants' union Volker Geyerwarned in comments published by the Rheinische Post newspaper on Saturday. He called for a review of control mechanisms and requirements for operators of critical infrastructure. The lower house of the German parliament, or Bundestag, is currently debating a reform of legal provisions to protect critical infrastructure. Under the government's proposal, operators would be required to report incidents in future and draw up plans for handling every conceivable risk. Dobrindt sees this as a second layer of protection. The German Association of Cities and Towns is also calling for a "national blackout reserve" from the federal government with mobile power plants. The head of the Police Union (GdP), Jochen Kopelke, in comments to The Pioneer website, advocated for a special fund of €100 billion ($116 billion) over 10 years to strengthen staffing, equipment and the protection of critical infrastructure such as energy facilities and undersea cables. (By Daniel Mollitor, Julia Kilian and Vanessa Reiber).