Formula 1's governing body has clarified how oil may be consumed by F1 cars.
That had followed a formal letter to the FIA, in which Mercedes asked Charlie Whiting if the 0.6kg per 100km oil consumption limit applied to the turbo.
"Yes," Whiting answered.
However, Germany's Auto Motor und Sport reports that despite the FIA clarification, Ferrari does not in fact need to modify its power unit.
"Questions about the battery remain," the report added, "but it should be clarified over the course of the weekend."
Sebastian Vettel told reporters: "There are always rumours. I trust Ferrari.
"I also trust the FIA that they would intervene if there was something they didn't like."
The season continues with the Monaco Grand Prix this weekend.