Andres Iniesta has accused Jose Mourinho of cultivating "hatred" between Real Madrid and Barcelona players during his time in LaLiga and says it led to "unbearable" tension within the Spain national team.
Mourinho spent three years in charge of Madrid after leaving Inter in 2010 and, during his reign, the Clasico rivalry became hugely bitter.
The most notable incident around a match occurred during a Supercopa de Espana clash in August 2011, when Mourinho appeared to poke Pep Guardiola's assistant Tito Vilanova in the eye amid a touchline fracas.
Mourinho then referred to Vilanova as "Pito" – Spanish slang for male genitalia – after the match, claiming he had no idea who Guardiola's assistant was, while Gerard Pique accused the Portuguese coach of "ruining Spanish football".
The majority of Spain's squad at the time came from Madrid and Barca and, although La Roja won Euro 2012 during Mourinho's Madrid stay, Iniesta has revealed the atmosphere became toxic thanks to the 'Special One'.
"You do not have to be from Barcelona or Real Madrid to know that this situation was unpleasant, and the key component in that story was Mourinho," Iniesta said on La Sexta's Salvados.
"You did not see it as a standard rivalry, it went beyond that. You saw hatred. That environment was cultivated, and it was unbearable.
"The Barca-Madrid tension provoked by Mourinho did a lot of damage to the national team and the team-mates."
