Warning: This story contains images of human blood, swastikas and Nazi symbols.

German police say they are investigating the appearance of swastikas painted with human blood and smeared on dozens of cars, some mailboxes and building facades in the central town of Hanau.

Police spokesperson Thomas Leipold said officers were alerted on Wednesday night, local time, when a man reported that he noticed the shape of a swastika applied in a reddish liquid on the hood of a parked car.

Officers later discovered almost 50 cars had been defaced in a similar way.

A special test quickly revealed that the substance was human blood.

The display of Nazi emblems, including the swastika, is illegal in Germany.

"The background is completely unclear," Mr Leipold said, adding that investigators did not k

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