"The person has been detained," a police spokesman told AFP without giving further details.

A fan threw a banana onto the pitch near the 30-year-old Brazilian international as he was about to take a corner during Barcelona's away match against Villareal on Sunday night.

Alves won praise for his reaction, picking up the banana to take a bite before getting on with the game and setting up a goal in Barcelona's dramatic come-from-behind 3-2 victory.

The incident sparked worldwide indigation, with Brazilian President Dilma Rousseff and FIFA president Sepp Blatter joining the anti-racist condemnation.

Villarreal said they had identified the fan who threw the banana, withdrawn his club membership and permanently banned him from their ground.