Gerard Pique was attacked by Spain fans during the nation's open training session, who jeered, whistled and insulted him.
"Pique, bastard, Spain is your nation," they chanted at the Catalan defender.
Pique had criticised the Spanish police for their heavy handed treatment of Catalans trying to vote during the referendum on Sunday.
Just 23 minutes of work
Julen Lopetegui decided to call an end to the session after just 23 minutes.