Ferrari says it would welcome a clarification from the FIA on the legality of its Formula 1 engine, after admitting it has become "annoyed" by recent speculation.
A number of teams have written to the FIA to seek clarification about design aspects of Ferrari's power unit that they want to develop for themselves but have not because they were unsure about the legality of those elements.
There have been suggestions rivals could now lodge a protest to get the matter sorted once and for all - and Ferrari team principal Mattia Binotto said he would be happy for that to take place to prove the engine is legal.
"There are two aspects," he said. "First we are annoyed by the rumours because in the past, as people got a great advantage on the power unit, the only reaction we had as Ferrari was simply to work even harder to improve our package. We never blamed them of cheating.
"I think other teams at the moment are faster than us in cornering. We are not blaming them in cheating in cornering, so I think I will be more happy if people focused on their own effort and developed their own car.
"On the other side we are relaxed because we know exactly what we are doing.
"We know we are legal and the FIA is controlling our package every single race. They are inspecting all the data that is available to them, and inspections have been made.
"So what should I say? Hopefully the FIA will clarify to everybody that what we have got is legal and we are not cheating."
Red Bull motorsport advisor Helmut Marko said the FIA needs to clarify the situation, especially because he has no explanation for how Ferrari has such an edge on the straights.
"We're on Mercedes' level in the race," Marko told Autosport of Honda's engine performance. "The only thing missing is the qualifying mode. This extraordinary performance increase of Ferrari is another topic."
Marko said the extent to which Ferrari's engine stands out over its rivals - which has been described by one team source as "ludicrous" - means some action must be taken.
"I'd rather not comment on suspicions. But when you look at the [power] curve and see how fast they are, it's amazing how an engine can stand out [like that]. Let's wait and see what happens there. The FIA has to clarify that," he added.
One interesting aspect about Ferrari's engine performance is that it appears it cannot make use of all of its gain every lap, with peak power often only seen in qualifying or on specific laps of the race.
But Marko says that overall, Ferrari's engine edge is there all the time.
"The effect is generally there, but they can't use it every lap," he said. "You saw in Suzuka when [Lewis] Hamilton was challenging [Sebastian] Vettel: DRS, slipstream, everything was useless. He wasn't able to pass him."