At least 76 police officers have been injured in clashes with protesters in Germany's city of Hamburg, where a G20 summit starts shortly, DW reported.

Three officers were taken to hospital, police said. There were also reports of injuries among protesters.

The clashes began when police charged at masked protesters at a "Welcome to hell" march attended by 12,000 people.

Authorities in Hamburg have published an official statement on the events of the past hour. According to the press release, police tried to separate about 1,000 hooded far-left protesters from the other marchers in order to ensure that the demonstration remained peaceful. The masked activists refused to comply, and became aggressive with officers, resulting in the use of water cannons and tear gas. 

Officers also reported rioting in the Altona and St. Pauli areas of the city, including property damage and burning cars. 

Security services have begun firing water cannon at protesters who have refused to comply with an order to remove face coverings and who have tried to continue their march through a police barricade. Hamburg police tweeted that protesters were throwing "bottles and objects" at them.