Helmut Marko suspects Ferrari is using a method to secretly listen in on Red Bull's race strategies during grands prix.

Red Bull's F1 consultant revealed his sensational suspicions on German RTL television after the Spanish Grand Prix on Sunday.

"We have noticed that Ferrari is doing some kind of espionage," said the Austrian.

Explaining his suspicion, Marko said: "We called Mark (Webber) into the box relatively late, and yet they (Ferrari) managed to get Alonso in as well. They had been able to respond to us."

It is believed Marko's suspicions hardened when Red Bull issued fake commands for its drivers to pit in Barcelona, and Ferrari still moved to respond.

Bild newspaper said Ferrari has not yet commented.