Mercedes motorsport boss Toto Wolff has expressed shock after two key employees were named by the FIA as sources of information which led to investigations of Ferrari's engine.

In recent races, Formula 1's governing body has been conducting tests of various parts including in Monaco when a sensor was placed inside the ERS amid claims the team had cleverly developed a design which allowed the Scuderia to exceed the permitted electrical power output.

On Sunday, the FIA said it was satisfied that Ferrari was in compliance with the regulations, but the Austrian was irked that race director Charlie Whiting would decide to name technical director James Allison and Lorenzo Sassi, both ex-Ferrari men now with the German manufacturer, as those who made contact.

"One of my roles is to protect my people and if certain individuals are named in the wrong context, then that is disturbing," Wolff said.

"Teams question the FIA every single day. I think it's not important to put it out that this person has questioned a legality topic.

"If you say a certain team has done that, then it is perfectly fine, that is modus operandi. Picking out individuals isn't the right thing."

As for Mercedes' stance on the legality of the Ferrari, in the wake of the FIA's work, the motorsport chief was happy to accept their conclusions.

"No judgement has been made on anything, no protest has been lodged, it's just a press statement," he claimed.

"We trust them. If they have looked at things, then it's fine."