FRANKFURT - German police said they detained 400 anti-capitalist protesters in Frankfurt on Friday for defying a ban on demonstrations against austerity policies implemented to tackle the intensifying euro zone debt crisis. The demonstration in the German financial capital was part of a four-day-long "Blockupy" protest, due to run until Saturday, against capitalism and swingeing austerity measures. "Hungry? Eat a banker," read one banner protesters held up outside the Messeturm skyscraper housing Goldman Sachs' offices. Reuters' Frankfurt office is also in the building. Police closed several main roads in Frankfurt - including a main artery into the city that passes by the Messeturm - and flooded the centre with officers. There was no violence. The protesters are angry at the misery they say governments are inflicting on people with their response to the crisis, which has intensified since inconclusive elections in Greece this month fueled concerns about its future in the euro zone. "The Greek austerity measures are making Greece go kaputt even faster," said protester Leonard Loch, 37, from Hamburg. The European Central Bank reported no trouble on Friday and commercial banks, many of whom have made contingency plans to cope with the protests, said their operations were running smoothly. "Our operating business is not curtailed. We were well prepared," said a Commerzbank spokeswoman. Police sealed off Deutsche Bank's headquarters. Germany's biggest bank said its business was unaffected. The ECB is at the centre of the policy response to the crisis and has faced calls from politicians, investors and protesters to do more. The central bank says it has already headed off a major credit crunch with unprecedented funding operations in December and February that unleashed over 1 trillion euros ($1.3 trillion) into the financial system.