The figurehead of the anti-Islam movement PEGIDA was detained at a London airport before being deported. He was due to speak at a far-right rally in central London's Hyde Park.
Lutz Bachmann said on his Facebook page that he was not allowed to enter the UK because he carried a copy of a speech by far-right Austrian activist Martin Sellner, who himself had been denied entry last week.
Both the dpa news agency and daily Bild say the UK's Home Office had confirmed to them that Bachmann had been detained at London's Stansted Airport and then deported back to Germany as his presence in the UK was deemed "not conducive to the public good," without going into more detail.
Speakers' Corner rally
Bachmann had planned to go to a far-right rally at Speakers' Corner in Hyde Park, where former English Defence League (EDL) leader Tommy Robinson read out Sellner's speech.
On Facebook, Bachmann says the fact that he was to attend the event was the sole reason for him being denied entry, as he had recently attended other events in London, Manchester and Birmingham – all in the UK.
Sellner, of the white supremacist Generation Identity group, and his girlfriend Brittany Pettibone, a YouTube commentator, were detained at London's Luton Airport on March 12 and refused entry into the UK.