In the last three days, more than 200 police officers have been injured. Some 143 people have been arrested and 122 taken into custody. The number of injured protestors was not available. On Friday night, special armed police had been deployed with sub-machine guns.
World leaders and officials are putting the final touches to a joint statement on issues ranging from trade to climate change on Saturday, the final day of the summit.
Merkel had wanted to show her commitment to free speech by hosting G20 leaders in Hamburg, a port city with a strong radical tradition, but images of burning cars and shops and streets awash with debris have raised questions about that strategy.
Hamburg residents inspected the destruction on Saturday and said they were angry the summit was taking place there.
"Merkel underestimated the protests. The least she can do now is come visit (the district of) Sternschanze and see the damage for herself," said Kai Mertens, a 50-year-old programmer.
"We are a very liberal district. But what they did here has nothing to do with the G20 or opposition to politics. They were hooligans and many were foreigners," added Mertens.
Police from across Germany have been brought to Hamburg to reinforce the local force. A 27-year old German suspected of attempted murder after pointing a laser pointer at a police helicopter was due to face a judge on Saturday, said police.
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