A shopper was asked to leave a supermarket after wandering the aisles dressed in full Nazi uniform.
Customers were left horrified when the man, wearing what resembled a black SS uniform complete with cap and red armband, visited an Asda store in Cambridge.
The manager of the Beehive Centre store asked him to leave after complaints from other customers.
Police were called to the incident at 2pm yesterday but a spokeswoman said: "By the time we got there he had already left peacefully."
A spokeswoman for Asda said: "We had a number of customer complaints so we asked him to leave the store."
Rosina Rusin, 60, from Milton, told the Cambridge News: "I was waiting in a queue when a lady came up and she was really quite distressed about it.
"People's mouths were falling open. You are not going to come out like that unless you want to draw attention to yourself."
It was unclear whether the incident was a Halloween prank.
Paul Dutton, from Cambridge, claimed responsibility using his Twitter account.
Under the name Operation Fail Safe, he said: "I wear a black SS armband in Asda twice a week for past three years.
"I've shopped in Asda since the place was opened twice a week, this is how Asda repay me for my loyalty."
He said he had wanted to hand out cards promoting his website, which explains the reasons for his fascination with Adolf Hitler.