Berlin police say that Luka Rocco Magnotta is being questioned and will be brought behind closed doors before a judge, who will read out the international arrest warrant later.
Officers arrested him on the site, he did not put up any resistance. He says he is the wanted person.
Interpol has placed Magnotta, who was last believed to be in Paris, on the equivalent of its most-wanted list.
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A memorial to honour the service of millions of men and women from Africa and the Caribbean during the two world wars has been unveiled.