Bristol City have arranged for an expert in graffiti removal to clean the gates at Bristol Rovers' stadium after "so-called City supporters" vandalised them.
The gates at the League Two club's Memorial Stadium were desecrated in graffiti with the messages "Merry Xmas from C.S.F" and "BS3 BCFC".
City said that "in the spirit of Christmas" they had sent someone to remove the graffiti and added: "Anyone found guilty of carrying out this mindless act of vandalism will face a lifetime ban from Ashton Gate."
In a club statement, Rovers responded by saying that they had been "heartened by the support" shown by their local rivals.
It went on to say: "It's disappointing that the good name of the majority of Bristol City supporters has been dragged through the mud by a mindless minority."
Both clubs have asked anyone with any knowledge of the incident to contact the police.