Lazio have condemned anti-Semitic behaviour by a number of their supporters during Sunday's Rome derby after Italy's sports minister expressed concerns.
As well as chanting from fans that sparked a complaint from the Jewish Community of Rome, one fan was seen to be wearing a shirt with the name 'Hitlerson' on its back, along with the number 88, which is used by neo-Nazis as numerical code for 'Heil Hitler'.
Efforts are under way to identify that Lazio fan, with the club recognising there is a problem. They indicated progress had already been made and said news of investigations would come within hours.
In January, Lazio were moved to condemned "despicable, shameful and anachronistic" racist abuse aimed at Lecce players Samuel Umtiti and Lameck Banda in a Serie A match.
Now they face more scrutiny over this episode.
Ruth Dureghello, president of the Jewish Community of Rome, wrote on Twitter: "A whole curve singing anti-Semitic chants, a 'fan' in the stands with the Hitlerson shirt and the number 88 and we, as always, are the only ones to get indignant and protest. Is it possible that everyone continues to ignore it?"
In response to that message, Italy's sports minister Andrea Abodi said: "Impossible to pretend nothing happened. I will do my part, as I feel I have to do. Respect is due and not negotiable!"
Lazio's Curva Nord was ordered to be closed for a game against Empoli after the abuse dished out to the Lecce players.
The club issued a statement on Tuesday in which they said Lazio were "at the forefront, especially under the current presidency, in publicly condemning, preventing and unreservedly repressing any discriminatory, racist or anti-Semitic demonstration or action".
It said the club "dissociates itself from any illegal and anachronistic behaviour of this type, as it is above all an injured party by such behaviour".
Lazio won the derby 1-0, with three players sent off, including one from each team at the end of the game.
Lazio said the anti-Semitic conduct amounted to "a dangerous germ" in which many who take part "do not even know the meaning and scope" of their actions.
The club said they had attempted to "avoid, isolate and contrast these phenomena", saying their commitment is to "inclusion, sportsmanship and respect for all".
Lazio's actions will be judged along with their words, and the club said they had observers at the Roma match, led by former deputy chief of police Nicolo D'Angelo, looking to identify those responsible.
The club said: "In the next few hours we will communicate the already positive results of our activity, trusting in the effective collaboration of the institutions responsible for safeguarding democratic rules."