Fingal Communities Against Racism are concerned that a house fire in Balbriggan last Sunday week has been used to 'push a racist agenda on social media'.
The cause of the fire has been investigated, but has still to be confirmed officially.
A spokesperson for the group said: 'Initial inspections identified it as an electrical fire, amplified when an oil tank in the back garden also caught fire.
'However, this has been portrayed on social media as a deliberate arson attack as a result of racially motivated gang violence.
'As a result of the fire, a local family lost their home and are in distress.
'However, this has not stopped inaccurate speculation on social media. Among these comments, we have seen posts by obviously fake accounts, by people who have never set foot in Balbriggan and by people connected with far-right parties.'
The group rejected online claims of a media blackout on the story saying: 'The reality, of course, is that house fires where nobody has been injured or killed and arson is not suspected, don't tend to make the national news.'
A group spokesperson said: 'The interest shown by individuals and groups linked with the far-right in a house fire in Balbriggan, a town which most of them have never visited, is a sign that something else is going on.
'The far-right use every opportunity to exploit people's fears, including fear of crime and anti-social behaviour, to stir up hatred and division and turn neighbours against each other.
'Their manipulation of social media to push their own agenda is sophisticated, including using multiple fake accounts and out of context video clips onto which they can project the narrative they want.
'These tactics are part of a pattern and have been used by the far-right in Ireland and internationally.
'We ask that people keep this in mind when browsing social media and speak up against attempts to divide our communities.'
the group added: 'Balbriggan is a diverse town made up of people from all over Ireland and other parts of the world who have made a home and are raising families here.
'The far-right has its own agenda in pushing an image of Balbriggan to the rest of the country that is relentlessly sinister and negative.
'Those propagating this agenda do not care about the town or any of its residents or how Balbriggan is perceived.
'We urge the community to speak out and refuse to let this far-right agenda erase the work of many good people in Balbriggan living and working side by side, trying to improve our environment and creating strong communities.
'Do not let a racist agenda define our town.'