Police cars have been set on fire, windows smashed and stones thrown at police and firefighters at a demonstration timed to coincide with the opening of the new European Central Bank headquarters in Frankfurt.
Anti-austerity protesters were gathering in the city under the #blockupy and #18M hashtags to demonstrate against the so-called "Troika" of the ECB, the European Commission and the International Monetary Fund who oversee bailout packages in the eurozone.

Several thousand riot officers pursued what they said was a minority of violence-minded activists as the bulk of protesters conducted themselves peacefully ahead of a rally in the city's main square. Some blocked bridges across the Main River or streets. Police said one officer was injured by stones thrown near the city's Alte Oper opera house

So far 350 people have been detained, Frankfurt police said Wednesday morning.

German broadcaster Deutsche Welle reported that 10,000 Blockupy protesters were expected to attend today's events.

Authorities have set up a security zone of barricades and barbed wire around the new ECB building.