Before the first game of the season, an unofficial flyer was distributed saying part of the Curva Nord was a "sacred place" where women were not allowed.

Lazio blamed "a few fans", adding: "We are against any discrimination."

The Italian FA (FIGC) told BBC Sport its prosecutor office has started an investigation over the leaflets.

On Monday, Italian news agency ANSA reported that police had identified the individuals responsible for the leaflet and could take action for sexual discrimination.

The pamphlet called for "women, wives and girlfriends" to avoid the first 10 rows of the stand.

"Those who choose the stadium as an alternative to the carefree and romantic day at the Villa Borghese [a Roman historic house and park], should go to other parts," it read.

The flyer was signed "Direttivo Diabolik Pluto", one of the leaders of a group of Lazio ultras known as the Irreducibili.

Lazio spokesman Arturo Diaconale, quoted by Italian media, said: "We didn't know anything about this [flyer]. It was an independent initiative by some of the Curva Nord fans."

"It's not the position of society. There is a huge number of Lazio fans, whereas this is an initiative from a few fans. We cannot always intervene to prevent politically incorrect demonstrations like this one."

Last season Lazio were fined after supporters displayed anti-Semitic stickers showing Holocaust victim Anne Frank in a Roma shirt.