Former Real Madrid favourite Iker Casillas claimed in an interview published on Friday he kept quiet for the good of the club during tough times leading to his 2015 departure for Porto.

Towards the end of his Real career Casillas, now 35, suffered many difficulties -- he fell out of favour with coach Jose Mourinho during 2012/13, struggled for form and was even jeered by sections of the Santiago Bernabeu crowd.

"I kept my mouth shut about what was going on for the good of the club," said Casillas, whose popularity peaked after Spain's World Cup win in 2010.

"You don't want to turn things into a circus at the first sign of difficulty," Casillas told Marca.

"In time, I understood that some people resented me for the Mourinho affair," explained Casillas, who has played 167 times for Spain.

"Staying at Real one year after another is not easy. Mental strength is key, you have to be able to take criticism at any moment."

Casillas played 510 first team games over a 16 season stretch with Madrid before leaving for Porto.