Police in Oldham asked swastika-wearing Nazi impersonators at a village pub to remove the symbols for fear they would spark disorder at an event attended by 10,000 people.
Officers attended the Granby Arms pub in Saddleworth on Saturday, and found a number of men dressed as Nazis.
They were participating in "Yanks Are Back", an American-themed wartime heritage event for military vehicle enthusiasts, being run in the area last weekend. No arrests were made and the event passed off without incident.
Greater Manchester Police said they had been informed last week about planned activity at the pub by a caller who said swastikas might be worn and could cause offence.
Inspector Danny Milovanovic from Saddleworth Neighbourhood Policing Team said: "While it is not illegal in the UK to display the symbol, the people wearing the swastika were told that it could cause offence.
"Police at the event were trying to prevent any potential disorder occurring as a result of this."
An organiser from the North West Military Vehicle Trust said they
voluntarily published a code of
conduct which prohibited the wearing of Nazi insignia at their "Yanks Are Back" event.
The spokesman said: "It's a show for military vehicles, not for people strutting about in swastikas - we don't advocate anything like that at all. Obviously the police were watching out, and did their job."
This is the second wartime event to be tarnished by Nazi impersonators after dozens of swastika-wearing men appeared at an event in Bury in May.