Anti-Irish banners were displayed by fans of Lazio during the club’s Champions League clash with Celtic.
Among the banners unfurled ahead of Tuesday’s game in Rome were ones referring to the famine, potato eaters and Fenians.
Supporters of the two clubs have a long history of animosity towards each other, with hard core Lazio “ultra” fans often linked to the far right.
One of the banners read: “The famine is over go home f***ing potato eaters”. Another was displayed outside the Stadio Olimpico and read: “Did the Fenian b******s take shower today?”
In a statement, UEFA said: "The official reports from all the matches played last night are currently being reviewed. Where matters are reported, proceedings are opened and should they lead to disciplinary sanctions being imposed, they are announced" on the governing body website.
Celtic was fined by UEFA following a previous match with Lazio in Glasgow. Members of the club's Green Brigade unfurled an "anti-facist" banner during the game, which was described as a “provocative message of an offensive nature” towards the Lazio support. The club was also fined after Palestinian flags were displayed during other European games.
The club is out of Europe this season following the 2-0 defeat at Lazio. The Italian club needed a late double to win, while Celtic had an extra time penalty award overturned following a VAR review.