There were scenes of confusion in the nightlife district of Saint Pauli as the black clad masked protesters choked the narrow alley while nervous drinkers looked on from pubs.

Hundreds of armoured riot police ran through the streets.

Police said the violence had broken out after they asked a hardcore of protesters to remove their masks.

The protesters planned to march to the city centre where the summit begins tomorrow.

Police said they could not continue unless they removed the masks.

There was a tense standoff for around half an hour while negotiations continued before the first smoke bombs were thrown.