Shopkeepers in Hamburg say that members of left-wing extremist groups have demanded money from them to save their businesses from destruction during G20 summit riots.

The Schanzenviertel is a small district in central Hamburg where police expect 10,000 left wing extremists to demonstrate during this week’s G20 summit. Shopkeepers in the area claim extremists have given them a choice: pay 20 euros and put up a poster supporting the demonstration or have your shop smashed, Die Welt reports.

Around the district, many shops have the pro-demo posters in the windows though it is not immediately clear how much they had to pay and who they were paying. Bruno Blockus, owner of local cheese shop Bruno’s Käseladen, said he had not heard of anyone coming to his shop demanding money but did have to deal with a cracked window from the evening before.

Many other shops plan on closing early and some, like clothing and footwear shops, have even put up signs asking the left-extremists not to smash up their businesses. Some shops are seen by the extremists as part of “gentrification” and can become targets for vandalism.

One resident of the area said that many had left in order to avoid the protests and the violence. “Many fear that things will get really bad, so they have left,” she said, adding: “I’m torn. I’ve been concerned about being alone this evening when it’s going on out there.”

The long-time resident also showed defiance to the extremists adding: “We live here. We are the Schanze. That’s why I’m staying here.”

Over the past week, police have raised concerns over the danger of violence from left-extremists in Hamburg.

Earlier this week a cache of weapons was found in Rostock that included flammable materials, multiple knives, illegal fireworks and other weapons. Police arrested two men in connection with the raid and are deciding whether or not to charge the pair with forming a terrorist organisation.

Police have also stated they expect left-extremists from all over Europe to descend on Hamburg with Ralf Martin Meyer, president of the Hamburg police warning of potential “massive attacks”.