Italy and Juventus centre-back Giorgio Chiellini says he is "ashamed" of the racist abuse Fiorentina fans aimed at Napoli players.
Kalidou Koulibaly and Napoli team-mate Victor Osimhen detailed on social media the racist abuse they received during Sunday's 2-1 win at the Florence club.
Andre-Frank Zambo Anguissa, on loan at Napoli from Fulham, was also reportedly targeted by home fans.
"We need laws and rules that are applied," said Chiellini, 37.
"I was ashamed, as an Italian and a Tuscan, also because Italy is not a racist country for me.
"Something more must be done, otherwise from outside we give a bad image of ourselves."
Senegalese defender Koulibaly has said racist fans must be "kept out of stadiums forever", while Nigeria forward Osimhen called for supporters to "understand how disgusting it is to hate an individual because of the colour of their skin".
Fiorentina said the club expressed "the most firm and harsh condemnation for the episodes of racism that took place" and say CCTV footage from the game will be provided to the authorities to help identify the "culprits".
The Italian Football Federation has opened an investigation into the incident.
An investigation has also been opened into alleged racist chants by Lazio fans aimed at AC Milan's on-loan Chelsea midfielder Tiemoue Bakayoko.