Mexico coach Miguel Herrera defended fans at the World Cup chanting a gay slur which is under investigation by FIFA.

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Herrera says Mexico fans shouting the slur as the rival team's goalkeeper takes a goal kick is not "serious."

"About the chants, we don't have anything to say, we are going to concentrate in working hard, that is what corresponds to us," Herrera said. "We support our fan base. They just do it to put pressure on the other goalkeeper.

"That chant was invented in the Mexican league by one team and all the Mexican fan base has adopted it, therefore I don't think it is something that serious.

"I think for us there is more important stuff to solve than a chant that is just an expression to put pressure on the other goalkeeper that has been taking place in Mexico since a long time ago."

Fare, the European fan-monitoring group, reported the chants at Mexico's 1-0 win over Cameroon in Natal. FIFA subsequently opened a disciplinary case against the Mexico federation, which is responsible for fan behaviour inside stadiums.

FIFA president Sepp Blatter and Brazil President Dilma Rousseff have pledged to use the World Cup as a platform to fight racism and discrimination.

The chant was also used during a Mexico-United States qualifying match for the 2004 Olympics.