Thirty-nine people were detained in Berlin on Saturday in connection with a far-right march commemorating the 30th anniversary of the death of high-ranking Nazi official Rudolf Hess.
More than 500 neo-Nazis had attempted to march to the site of the former prison in Berlin's western district of Spandau where Hess died in 1987, but were blocked by left-wing groups and local residents.
Police said on Sunday that 35 of those detained belonged to the far-right march, while four were taking part in the counter-protest.
Twelve of the far-right protesters are being investigated for displaying forbidden symbols.
Others detained are being investigated for breach of the piece, assault, resisting arrest, drug offences and breaking the law on public assembly.
The march was accompanied by about 1,000 police officers and passed largely peacefully.