Real Madrid forward Cristiano Ronaldo has accused referee Undiano Mallenco of being biased towards Barcelona during El Clasico on Sunday.

Los Blancos had Sergio Ramos sent off in the 63rd minute and saw Barca awarded two spot kicks during their 4-3 defeat to Gerardo Martino's side at the Santiago Bernabeu in La Liga.

"Undiano Mallenco is not suitable for games like this," Goal.com quotes the 29-year-old as saying. "We were playing against 12. It's always the same.

"It's like they don't want us to win and wanted Barcelona back in the title race. I am not looking for excuses but I don't want to stay quiet on this. The referee was not at the required level for a big game like this.

"I have been here for five years now and I know how things work. If Barcelona had lost, they would have been out of the title race. I have never seen Real Madrid being favoured by the referees."

The win for Barcelona means that they are now a point behind Real and Atletico Madrid, who are level on 70 points at the top of the league table.