By Sakari Suoninen and Joern Poltz
FRANKFURT (Reuters) - 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.
It is pressing governments to act.
"The ECB shouldn't give the cheap money to banks but rather to countries," said Guenther Stamer, 62, a social worker from Kiel.
Some luxury goods boutiques on Frankfurt's most prestigious shopping street closed and boarded up their windows due to the protest, though there were no signs of damage.
The English Theatre, which is close to the ECB, cancelled performances for Friday and Saturday due to the demonstration.
Friday's protest followed a legal scrap between activists and authorities over whether the demonstrations should be allowed to proceed.
A court on Monday gave the go-ahead for a rave dance party organized by protesters on Wednesday and protests scheduled for Saturday, but ruled against them taking place on the other days.
On Wednesday, police peacefully removed demonstrators from outside the ECB's Frankfurt headquarters and detained 150 demonstrators on Thursday for defying a ban on protests.
Frankfurt police have drafted in reinforcements from other German states to cope with the protests. Some 5,000 police are ready to be deployed.
($1 = 0.7869 euros)
(Additional reporting by Edward Taylor and Arno Schuetze; Writing by Paul Carrel; Editing by Sophie Hares)