Ahead of Lazio's Serie A curtain raiser against Napoli last weekend, Laziale 'ultras' group handed out flyers stating that the stand they occupy in the Stadio Olimpico stadium is a "sacred place" where women are not welcome.
"We have always experienced the first rows as trenches. Women, wives and girlfriends are not allowed inside, so we ask them to sit from the tenth row back," read the message on the flyer, which was widely circulated on social media networks.
"Those who choose the stadium as an alternative to a carefree, romantic day at the (park), should sit elsewhere."
A Rome police spokeswoman told the Thomson Reuters Foundation that detectives have identified two suspects and referred the case to prosecutors for possible breaches of the country's anti-discrimination laws.
The Italian football federation (FIGC) said it was also investigating the incident, which former Lazio and Italy women's national team striker Carolina Morace said was "unjustifiable".
"We are (back) to the Middle Ages," she told news agency Ansa. "I hope these people will be banned from the stadium".
A spokesman told Italian media that the pamphlets were the work of a few fans, and did not reflect the position of the club.
Women often complain of widespread sexism in Italy, which ranked 82nd of 144 countries in a 2017 gender equality report by the World Economic Forum - the third worst in western Europe.
Almost one in two women in Italy has experienced sexual harassment, according to the national statistics agency ISTAT.
Luisa Rizzitelli, head of a national association for female athletes, said in an opinion piece online it was "disheartening" to see that in 2018 "there are still people who think they can decide where and how women can watch a football game".
In nearby Spain, Barcelona football club's first mixed-sex tour got off on the wrong foot last month when male players flew business class while women players were relegated to the back of the plane, with the disparity drawing criticism on social media.