(AP) FIFA has warned Mexico about the conduct of its fans after discriminatory chants at the Confederations Cup.

The homophobic abuse was heard during Mexico's opening game against Portugal in Kazan on Sunday despite FIFA warning on the eve of the World Cup warm-up tournament that there would be tighter monitoring of offensive incidents in stadiums.

FIFA says its disciplinary committee chairman Anin Yeboah "decided to impose a warning on the Mexican Football Federation for the misconduct of a small group of Mexican fans in relation to insulting and discriminatory chants."

Mexico has been sanctioned over gay slurs by fans in the current World Cup qualifying campaign.

Mexico plays New Zealand in its second Confederations Cup game on Wednesday.