Formula One race director Charlie Whiting has once again insisted that the FIA is happy with the operation of Ferrari’s hybrid system, despite ongoing questions being asked by rival teams.

The FIA announced a few weeks ago in Monaco that, despite thorough investigation, there was nothing to suggest that the Italian team was doing anything wrong or breaching any rules.

However, rival teams still aren't happy and they are continuing to question the recent strong performances from Ferrari, but also from their customer teams Haas and Sauber.

"Something is going on there, it's not normal," said Renault's Nico Hulkenberg.

"Since a couple of weekends, since France I think, all Ferrari-powered cars have a lot of power all at once.

"It's difficult for us against Haas, because in the corners we are at eye level or better but on the straights we lose a lot."

Whiting and other key FIA representatives had a meeting with Mercedes officials at the team's motorhome in Hockenheim.

"We are entirely satisfied with everything on that front, as we said in Monaco," said Whiting.

"Some teams have been asking further questions and we were just there to try and help them have some peace, if you like."

Asked if Mercedes had questions about legality, or just wanted to know where the limits were for its own development, Whiting said: "Again, those discussions are private.

"I don't think I should be telling you. If you want to talk to Mercedes, they'll tell you but I think what goes on behind closed doors should remain behind closed doors."

Mercedes boss Toto Wolff would not be drawn on the discussions, implying that it was a routine gathering.

"The exchange you're having with the FIA and some of the other teams, or engine manufacturers, is on a regular basis," he said.

"It's more visible if you do it on a weekend, on track, in the motorhome, but it's completely regular business to discuss various technical topics."

While, on the other hand, Renault Sports boss Cyril Abiteboul admitted that the data suggests that Ferrari is doing something "strange", but stressed that this doesn't mean that the team is necessarily doing anything wrong or more importantly anything illegal.

"First we know we have a power deficit, which up until now was against Mercedes," he told Motorsport.com.

"They are still here but we see indeed that Ferrari has taken the upper hand, so congratulations to Ferrari in that battle, which is more a technical battle, but less visible. The step that they have done is amazing.

"It's a step that they have done to a certain degree that does not go with a hardware introduction, it's also a step that we see across all three teams, not just Ferrari, which is not necessarily a battle for us, but also Haas and Sauber, which are more of a battle for us.

"Clearly we are scratching our heads, because we look in particular at the GPS profile, and we we see indeed that it's really strange what they are doing.

"But doing something strange doesn't mean that it's illegal. I think we must give credit to what they have done, and that should be an extra commitment to work harder, and try and do the same step on our side."