A man set fire to a box of books on Nazism that was part of a Berlin monument dedicated to the Jews deported by the Nazis, city police said Saturday.

"Nearly all the books have been burned," the police posted on Twitter, now rebranded as X, adding that they had opened an investigation into the incident.

Police said two witnesses had reported seeing a man at dawn setting fire to the box of books -- an old telephone booth converted into a mini-library.

The box of books was part of a memorial known as "Platform 17" in Grunewald station, Berlin. It was from Platform 17 that 50,000 German Jews were deported to Nazi concentration and death camps at Riga, Warsaw, Auschwitz and Theresienstadt from 1941 onwards.

As part of the memorial, inaugurated in January 1998, Platform 17 now has 186 plaques alongside the track detailing the departure date of each train, the number of Jews on board and their final destination.

The Berlin city website explains that the undergrowth that has sprouted around the tracks forms part of the memorial. "It is the symbol that no train on this track will ever leave this station again."