The posters were displayed around the Girona Avenue area of the town, with Councillor McCaw saying their appearance was “disgusting”.
“It is clear these posters and their underlying message are trying to sow division among people in Portrush. This has always been a friendly and welcome town, with residents and visitors from all over the world.
“Posters containing slogans such as ‘Thank you for not mixing’ or ‘Save our race’ have no place here, or anywhere. Nobody has the right to make others feel unwelcome or to encourage this kind of division.
“As we look forward to welcoming people from across the world to Portrush for the Open in July, and as the tourist season is fast approaching, we stand up to anyone trying to push this kind of negative image of our town. We need to remain a united community. I would urge anyone with information on those behind these posters to give it to police immediately.”