Fifa have opened disciplinary proceedings against Mexico over alleged discriminatory chanting by fans at the World Cup.

The governing body said it had already opened the case against Mexico before the anti-discrimination Fare network made an official complaint about four instances of alleged supporter misconduct.

The claims against Mexico centre around the use of the word “puto” (used as a homophobic slur), which has been heard in games in Fortaleza and Natal.

Fare has brought 4 incidents of racism or homophobia at #WorldCup2014 to the attention of FIFA this morning. — Fare (@farenet) June 18, 2014

Fifa said in a statement: “We can confirm that we have been contacted by Fare. Prior to this, disciplinary proceedings were opened against Mexico for improper conduct of spectators during the match Mexico v Cameroon. As the proceedings are ongoing, we are not in a position to comment further.

“Fifa takes a firm, zero-tolerance stance against any form of discrimination and racism and this is enshrined in the Fifa Statutes.”

Fifa are understood to have also received complaints about alleged homophobic chanting by Brazil’s supporters, and alleged antisemitic behaviour by fans of Croatia and Russia.