A spate of graffiti about the September 2001 attacks in America has appeared around Bristol.
Graffiti is criminal damage
The spray-painted words '9-11 = iNSiDE JOB!' have been spotted across the north of the city.
Fly-posters and stickers making the same claim predated the spray-painting in the same area.
Neither the police nor the city council has received complaints about the graffiti, although a police spokesman said graffiti was criminal damage.
A spokeswoman for the council said they would look into it.
"If it was offensive, we would remove it," she added.