Atletico Madrid goalkeeper Jan Oblak has demanded Real Madrid "leave referees in peace" after Los Blancos questioned the integrity of Spanish officials earlier this week.

Last Saturday, Madrid fell to a surprise 1-0 defeat to lowly Espanyol in LaLiga, a result that allowed neighbours Atletico to pull within one point of them at the summit.

Espanyol's winning goal was scored by Carlos Romero, who Madrid thought should have been shown a red card for a lunge from behind on Kylian Mbappe earlier in the game.

Carlo Ancelotti called that decision "inexplicable", and Madrid subsequently sent a letter of complaint to the Spanish Football Federation (RFEF) and Spain's High Council for Sports.

In the letter, the 15-time European champions made the extraordinary claim that officials' decisions are "rigged" against them, saying: "Decisions against Real Madrid have reached a level of manipulation and adulteration of the competition that can no longer be ignored."

Other clubs in LaLiga have reportedly called for Madrid to be punished for attempting to put pressure on officials, and Oblak – whose team face Madrid in a huge derby on Saturday – says referees must be allowed to do their jobs.

"The best way is to leave referees in peace and that way they can do their job at their best possible level," Oblak told ESPN on Thursday. 

"That is the most important thing for football, not just for the teams, but for everyone. It's not the referees who will decide the game."

LaLiga president Javier Tebas has also taken aim at Madrid, saying the club have "lost their heads" and accusing them of looking to damage the league's reputation.

"Real Madrid wants to harm the competition, not just the refereeing group," he said at a meeting of clubs on Thursday, which Madrid refused to attend.  

"They have built a story of victimhood and I think the cherry on top was the letter they published the other day.

"The issue has been blown out of proportion, they have lost their heads. Football doesn't revolve around Real Madrid."

Madrid responded to their defeat at Espanyol by beating Leganes 3-2 in the Copa del Rey quarter-finals on Wednesday. Atleti made the competition's last four 24 hours earlier by trouncing Getafe 5-0.