Police are looking into whether BNP leader Nick Griffin published the address on Twitter of a gay couple at the centre of a landmark legal ruling.
The MEP is alleged to have posted where Michael Black and John Morgan live on the social networking site.
He is also said to have called for a demonstration to be held outside their home.
Cambridgeshire Police said it is now investigating the incident.
The alleged tweets, under the username @nickgriffinmep, came after the couple's win against the owner of a bed and breakfast accomodation who had refused to let them stay in a double rooms because of her religious beliefs.
The couple, from Brampton, near Huntingdon, sought damages from Susanne Wilkinson, after she would not let them have the room at the Swiss Bed and Breakfast in Cookham, Berkshire.
One of the complained tweets read: "So Messrs Black & Morgan, at (their address). A British Justice team will come up to Huntington & give you a.....
"...bit of drama by way of reminding you that an English couple's home is their castle. Say No to heterophobia!"